(CNN) -- As anti-American furor raged in the home of the Arab Spring, the top U.S. diplomat on Friday sternly warned countries where the unrest has been most pronounced: Stop the violence and seek justice against those attacking diplomatic missions, or else the United States will.
From Morocco to Malaysia, thousands of Muslims have taken to the streets in recent days.
Many have fumed over what Secretary of State Hillary Clinton described Friday as an "awful Internet video that we had nothing to do with" -- an inflammatory anti-Islam film posted online this summer, and publicized in recent days.
The 14-minute film trailer, which was privately produced in the United States led by a man federal officials identified as Nakoula Basseley Nakoula, mocks the Prophet Mohammed as a womanizer, child molester and ruthless killer.
Protesters, notably, haven't all been violent and they represent a fraction of their respective nations' populations: In Egypt, for example, a few thousand have clashed with security forces outside the U.S. embassy in Cairo, in a nation of more than 80 million people.
Still, confrontations that have occurred have aggravated relations between the U.S. and other nations, and led to a number of deaths -- including those of the U.S. ambassador to Libya and three others killed in an attack Tuesday in Benghazi, Libya. The U.N. Security Council issued a statement Friday expressing "deep concern" over attacks on diplomatic posts, calling them "unjustifiable regardless of their motivations."
Clinton said such assaults are misguided, and fly in the face of the better society many in these countries recently fought for when they overthrew authoritarian rulers.
"The people of Egypt, Libya, Yemen and Tunisia did not trade the tyranny of a dictator for the tyranny of a mob," she said Friday during a ceremony in which the bodies of the four killed in Benghazi returned to the United States.
"Reasonable people and responsible leaders in these countries need to do everything they can to restore security and hold accountable those behind these violent acts. And we will ... keep taking steps to protect our personnel around the world."
The contrast between then and now was especially evident in Tunisia, birthplace of the Arab Spring.
Two years ago, the self-immolation of street vendor Mohamed Bouazizi set off a wave of popular unrest that soon led to the downfall of Tunisia's longtime leader, President Zine El Abidine Ben Ali.
On Friday, hundreds of demonstrators -- some belonging to the Salafi movement -- were back on the streets of Tunis, setting their sights on the U.S. Embassy.
They burned cars, praised late al Qaeda leader Osama bin Laden, stormed the embassy complex and replaced the U.S. flag with their own black banner, according to witness accounts. A nearby American school was "unusable" after being badly damaged, U.S. State Department spokeswoman Victoria Nuland said.
Two people were killed and more than 20 were wounded, interim Tunisian President Al-Munsif Al-Marzouki said late Friday on state-run TV.
While asserting the anti-Islam video that stirred the outrage "cannot be justified by claims of freedom of opinion and speech" (and adding Tunisia would try to sue the filmmaker), al-Marzouki condemned the "irresponsible, unjustified acts of violence by protesters" who wrongly blamed the U.S. government for the film.
Anti-American protests -- some peaceful, some violent -- were hardly confined to Tunisia. Here's a breakdown of events Friday around the Muslim world:
-- In the Egyptian capital of Cairo, a running battle between police and protesters continued into its fourth day. There was a peaceful demonstration at Tahrir Square, but unrest erupted outside the U.S. Embassy as riot police continued to clash sporadically with protesters.
The Interior Ministry issued a statement saying 53 security officers were injured Friday, seven by birdshot. And birdshot was blamed for the death Friday of one protester, whom the Egyptian ministry described as an ex-convict with an extensive criminal record. Thirty of the 142 people arrested since the unrest began Tuesday remain in custody.
-- In Egypt's northern Sinai, Islamist Bedouins staged a protest, a security official said. Militants carrying automatic weapons breached a base housing international peacekeeping troops and burned trucks and a watch tower. The armed clashes injured at least four troops and an Islamist Bedouin. The 1,500-troop mission has supervised the security of the Egyptian-Israeli peace treaty since 1979.
-- In Sudan's capital, Khartoum, protesters managed to get inside the compound containing the German and British embassies. They did not breach the British building, but some got into a German Embassy and pulled down a German flag before police with tear gas forced the crowds to retreat.
At least two people were killed after they were run over by a police vehicle, reported the state-run SUNA news agency, calling their deaths "an accident." Fifty policemen were injured and protesters set a police car on fire, the report said, citing police forces.
U.S. Vice President Joe Biden later Friday called his Sudanese counterpart, Ali Osman Taha, to "express his concern" and press Sudan to protect diplomats and their facilities in the African nation.
-- In Yemen, police opened fire Friday to stop protesters from reaching the U.S. Embassy in Sanaa, eyewitnesses told CNN. Yemeni government forces were sent in and, by late in the day, surrounded the U.S. embassy compound, Nuland said.
-- Afghanistan saw its first demonstrations Friday. Hundreds in eastern Nangarhar province burned a U.S. flag and chanted "Death to America" and "We condemn the film." The demonstration lasted about an hour and ended peacefully, a local official said. The Afghan government has ordered an indefinite block of YouTube to prevent people there from watching the clips and staging violent protests.
-- In Gaza, several thousand people gathered after Friday prayers and chanted anti-American and anti-Israeli slogans. Protesters burned American and Israeli flags, as well as effigies of U.S. President Barack Obama.
-- In Syria, hundreds of protesters outside the U.S. Embassy in Damascus waved placards that condemned the film and blamed the U.S. administration for allowing the production and broadcast of it, according to the state-run Syrian Arab News Agency.
-- In Lebanon, hundreds of demonstrators took to the streets in the northern city of Tripoli, where they attacked and burned down a KFC restaurant. One person was killed and 25 others were wounded in scuffles between protesters and security forces.
There also were protests in Iran, Iraq, Pakistan, Turkey England, Israel, Nigeria, Malaysia, Bangladesh and India, among other locales.
These demonstrations were not unexpected: On Thursday, the FBI and the U.S. Department of Homeland Security warned there could be more violence "at home and abroad as the film continues to gain attention."
And days before violent protests Tuesday in Egypt, the U.S. Embassy in Cairo was warned by the American intelligence community of concerns about the "Innocence of Muslims" film that sparked the outrage, a U.S. official told CNN. The cable sent to the embassy did not mention a specific threat. It only warned about the existence of the online movie and the fact that it was gaining attention.
U.S. authorities have discounted as false a producer's claims to news outlets that the filmmaker was an Israeli who made the movie with financing from more than 100 Jewish donors. Israel's government denies that the film's maker is Israeli.
Despite the firm condemnation by U.S. government officials, some in the Muslim world -- especially those raised in regimes in which the government must authorize any film production -- cannot accept that a movie like "Innocence of Muslims" can be produced without being sanctioned by Washington, said Council of Foreign Relations scholar Ed Husain.
"They're projecting ... their experience, their understanding (that) somehow the U.S. government is responsible for the actions of a right-wing fellow," said Husain, a senior fellow at the New York think thank.
Latest on the investigation into U.S. ambassador's killing
Sources tracking militant Islamist groups in eastern Libya say the Tuesday attack that killed Ambassador Chris Stevens and three other Americans was most likely carried out by a pro-al Qaeda group. Obama has vowed that "justice will be done."
Four people have been arrested in connection with the attack, although they were not directly tied to the killings, said Monem Elyasser, the chief aide to the Libyan prime minister.
Elyasser did not release the identities nor did he detail the allegations against the four people in custody.
The evidence leading to the arrests was based partly on witnesses, but "mostly pictures that were taken around the compound at that time," Libyan Prime Minister Mustafa Abushagur told CNNI's Christiane Amanpour.
Mohammed al-Megaryef, president of Libya's General National Congress, said he was "100% sure that (the attack) was preplanned, and it was carried out with the intention to inflect all this damage, all this havoc" -- including rocking relations between Libya and the United States. He called for "the international community" to help Libyan security control militant groups behind such violence.
Contrary to al-Megarye's assertion, White House spokesman Jay Carney said Friday that U.S. authorities know of "no actionable intelligence" that indicates the Benghazi attack "was planned or imminent."
The United Nations has asked its non-Libyan staff to temporarily leave Benghazi and head to Tripoli as a "precautionary measure," said Radhia Achouri, head of the U.N. Mission in Libya.
And since Tuesday's assault, the U.S. has announced it will fly unmanned drones over Libya and dispatch two warships carrying guided missiles -- the first of which has already arrived off the coast of Libya.
U.S. Marine teams have been dispatched to Libya, Yemen and Sudan to safeguard American diplomatic posts in those nations, according to U.S. officials.
"Although these security forces are equipped for combat, these movements have been undertaken solely for the purpose of protecting American citizens and property. These security forces will remain in Libya and in Yemen until the security situation becomes such that they are no longer needed," Obama said.
And a senior State Department official said the United States is working with the Tunisian and Sudanese governments "to ensure the necessary resources to deal with the situation at our missions there."
CNN's Harmeet Singh, Kareem Khadder, Mohammed Tawfeeq, Arwa Damon, Ben Wedeman, Hamdi Alkhshali, Brian Walker and Elise Labott, and journalists Masoud Popalzai, Zied Mhirsi, Isma'il Kamal Kushkush contributed to this report.