Marching past US Marines who stood guard at the presidential palace, the protesters on Friday shouted "long live Aristide" and "Down with George Bush."
The protesters vented anger against "occupation of their homeland".
It was the biggest show of force since Aristide fled the country on 28 February, as rebels prepared an assault on the capital after capturing sizeable parts of the country.
The latest protests underlined the deep divisions in strife-torn Haiti.
The armed offensive by the rebels followed months of opposition-sponsored street protests against Aristide.
US Marines arrived the day Aristide left, followed by French and Chilean troops forming the vanguard of a UN peacekeeping force.
Aristide, now in exile in Central African Republic, has alleged that he was forced out by the United States. He also accused France of colluding with Washington.