The US embassy's outer office was set on on fire on Thursday and several windows were broken [in Belgrade.]
Western officials have called on Serbia to do more to protect diplomatic offices in Belgrade, after overnight rioting, which left at least one person dead, damaged a number of embassies.
Boris Tadic, the Serb president, called an emergency meeting of the national security council on Friday, saying such riots must "never happen again".
He said in a statement: "There is no excuse for the violence. Nobody can justify what happened yesterday."
Rioters attacked US and other Western embassies in the Serbian capital late on Thursday to protest Kosovo's unilateral declaration of independence last weekend.