Armed supporters of Aristide shot and injured 11 people who were protesting against the government in the southwestern city of Petit-Goaves, according to a radio report citing medical officials.
At least 15,000 people marched through the capital, in the second consecutive day of protests, calling for Aristide to step down.
One person was killed in the town of Gonaives on Monday during clashes between police and an opposition militia.
Organiser Andre Apaid, of the Democratic Platform, said the protesters wanted to send a message to the Caribbean Community (Caricom), which at the weekend urged Haiti's rival groups to seek a peaceful end to the tensions that have been mounting since disputed May 2000 elections.
The opposition has rejected Caricom's efforts insisting that Aristide and his government must step down.
Protests for and against the government have mounted in recent weeks, with several of them ending in violence.
The National Police announced it would restrict protests to one section of Port-au-Prince, saying it was taking this step out of security concerns.
Demonstrations would have to be held at Place d'Italie, a vast ocean-front esplanade located between the US embassy's chancery and the Haitian foreign ministry.
Protest organisers refused to meet with the National Police to discuss demonstration routes, police said in a statement.
"Some demonstrations are followed with violence," police said. "According to information gathered by (the National Police's) intelligence service, individuals with bad intentions are ready to continue dishonest acts to disrupt schools and stop peaceful citizens from going about their business," police said.