They also called for sending military observers to the predominantly ethnic Albanian province of Kosovo in Yugoslavia, before fighting spread there.
Security forces appeared at a loss as to how to reassert their control over the predominantly Albanian province as crowds attacked Serbian neighborhoods for a second night.
Serbia acted a day after suspending the Parliament and Government in the predominantly ethnic Albanian province, Kosovo.
Unlike the war in Bosnia, the Yugoslav Government's campaign in the predominantly ethnic Albanian province of Kosovo lacks dug-in front lines separating warring armies.
They are volunteers on their way to Kosovo, the predominantly ethnic Albanian province of Serbia that is fighting to become a separate state.
Kosovo would be explicitly left in Belgrade's sovereignty, with no reference to any referendum on its future status, a form of absurdity in a province so heavily Albanian.
The head of the Serbian government's negotiating team said the American proposals would pave the way for independence for the ethnic Albanian province in Serbia.
The Yugoslav President, Slobodan Milosevic, revoked the autonomy of the overwhelmingly Albanian province in 1989.
They are all lining up against Hungarians in Transylvania, which is similar in size to Kosovo and has a similar population to the Albanian province.
It was the third day of unrest in the predominantly Albanian province, where 28 people died in riots last year.