But the rebels led by Guy Philippe almost immediately rejected the demand, saying they would not disarm.
"I will not lay down my arms, despite international pressure," Philippe said during an open-air meeting in Petionville, south of Port-au-Prince.
His quick rejection followed a statement from the US State Department for an immediate disarmament.
"All illegal and armed groups should lay down their arms," State Department spokesman Richard Boucher said. "The rebels need to disband and go back to their homes."
He said Washington remained favourable to holding talks with Haiti's democratic opposition, but "the people who are in armed gangs, thugs, the remnants of the former army, the death squads have no role in the political process so far as we are concerned."
The US call for disarmament came as the armed rebels announced they would arrest Haitian Prime Minister Yvon Neptune who stayed on as the country's head of government after President Jean-Bertrand Aristide went into exile.
Rebels loyal to Guy Philippe said they would detain Neptune to try him for unspecified crimes.
Meanwhile, Aristide continued to make news in exile as he did in his final days in power.
"The people who are in armed gangs, thugs, the remnants of the former army, the death squads have no role in the political process so far as we are concerned"
US State Department
Responding to Aristide's accusations he was being held against his wishes in the Central African Republic's capital Bangui, the country's Communications Minister, Parfait Mbaye, insisted the exiled president was not a prisoner.
"Jean-Bertrand Aristide is not a prisoner. He is free to move around," the minister said.
Having left Haiti in the face of worsening anarchy, Aristide accused the US of plotting his ouster. In an interview with an American television channel, he said he was forcibly put on a plane and flown to Bangui.
The ousted president also told some US lawmakers he was being held against his will at the presidential palace in Bangui.
Witnesses said about 30 armed presidential guards were deployed at the entrance to the palace. Journalists were barred from approaching it.
Mbaye said Aristide, together with his wife, was staying in a suite of the palace, where he had a television and telephone.