Hundreds of students poured into the streets of Kabul on Sunday shouting anti-US slogans to protest against a film mocking Islam that has sparked deadly riots in the Middle East and North Africa, police said.
The protesters, mostly students from Kabul University, shouted "death to America" as they blocked a road near their compound.
"The demonstration is peaceful. There are about 1,500 students who have gathered here and are protesting the film," local district police chief, Faizullah, said.
Faizullah, who like many Afghans uses only one name, added that security was tight near the scene in the Afghan capital.
In the western city of Herat, hundreds of other protesters set fire to pictures of US President Barack Obama and an American flag to denounce the amateur film produced in the United States, but dispersed peacefully, an AFP reporter said.
Afghanistan has a history of street protests turning violent, particularly over perceived insults to Islam, but so far isolated protests over the film, the Innocence of Muslims, have been calm.
On Friday, protesters in eastern province Nangarhar set fire to an effigy of Obama, where tribal chiefs and Islamic clerics announced a $100,000 bounty on the head of the producer of the film.
In Afghanistan, riots triggered over the accidental burning of copies of the Koran, Islam's holy book, at a US base killed around 40 people earlier this year.
In cities across the Muslim world protesters have vented their fury by targeting symbols of US influence ranging from embassies and schools to fast food chains.
Washington has recalled non-essential staff from embassies in Sudan and Tunisia and Al-Qaeda has called for more attacks on US targets to avenge the film.