The embassy warned Americans to avoid crowds, blaming tensions resulting from recent violence in Kosovo.
State Department spokesman Adam Ereli said in Washington Serbian authorities are providing additional security to the embassy.
Reports from Belgrade say the embassy used tear gas and stun grenades to disperse rock-hurling Serbian protesters, who overturned cars and garbage cans and destroyed buses near the facility.
Serbian nationalists consider the United States the biggest ally of Kosovo's ethnic Albanians, who demand independence from the Serbia-Montenegro union.
State Department spokesman Adam Ereli said in Washington Serbian authorities are providing additional security to the embassy.
Reports from Belgrade say the embassy used tear gas and stun grenades to disperse rock-hurling Serbian protesters, who overturned cars and garbage cans and destroyed buses near the facility.
Serbian nationalists consider the United States the biggest ally of Kosovo's ethnic Albanians, who demand independence from the Serbia-Montenegro union.