Fury about a film that insults the Prophet Muhammad tore across the Middle East over the weekend with protesters attacking US embassies and burning American flags as the Pentagon rushed to bolster security at its missions.

Hundreds of riot police sealed off the area near the US embassy in Cairo on Saturday and the interior minister said he would restore calm after four days of clashes between police and Egyptians incensed by the film. A 35-year-old protester was killed and dozens were injured in clashes overnight.

At least seven people were killed on Friday as local police struggled to repel assaults after weekly Muslim prayers in Tunisia and Sudan, while there was new violence in Yemen and across the Muslim world.

The Taliban claimed responsibility on Saturday for an attack against a sprawling British base in southern Afghanistan that killed two US Marines, saying it was a response to the film and also because Britain's Prince Harry is serving there.

President Barack Obama on Saturday rejected any denigration of Islam but said there is no excuse for attacks on US embassies, insisting he will never tolerate efforts to harm Americans.

"I have made it clear that the United States has a profound respect for people of all faiths," Obama said in his weekly radio address. "Yet there is never any justification for violence .... There is no excuse for attacks on our embassies and consulates."