Demonstrators angry with a movie they judged to be blasphemous attacked the US consulate in Benghazi, Libya, killing the US ambassador to Libya, Christopher Stevens.
Three consular officials were also killed during the attack on Tuesday night.
Protests have continued today in Egypt, Tunisia, Iran, Iraq and other parts of the Middle East.
In the Yemeni capital, Saana, one protester was killed and four others were wounded when police tried to control a crowd storming the American embassy.
In France, the French Council of the Muslim Faith (CFCM) has condemned the low-budget film, which was made by a man who claims to be a US-Israeli Jew.
But the Council’s President, Mohammed Moussaoui, says there is no justification for the attacks on American embassies.
“It is undignified to pretend to defend the dignity of Islam while undermining the lives of innocent people,” he says in a statement.
“While strongly condemning the broadcast of this disgraceful and despicable film, the CFCM calls on Muslims to…use just and legal means to defend their religion.”
Dalil Boubakeur from the Grand Mosque of Paris also called for “calm and vigilance”, and urged Muslims to “take the higher ground with regards to this despicable infamy.”
“There is certainly anger around this issue. I hope there won’t be protests in France,” he told news agency AFP. “It only takes a fanatic or two for it to deteriorate.”
The United States has stepped up security at its consulates around the world in response to the controversy.
US President Barack Obama has also called the leaders of Egypt and Libya to discuss security cooperation.
American officials are investigating the possibility that the deadly attacks on Tuesday night were pre-planned, rather than spontaneous demonstrations against the film.