The plan would have Aristide share power with his foes and form a new government. He agreed to the plan over the weekend but has emphasized that he will not leave office until his term expires in February 2006.
Several leaders in the Democratic Platform opposition coalition said they rejected the deal.
"There will be no more delays. Our answer remains the same. Aristide must resign," Maurice Lafortune, president of the Haitian Chamber of Commerce, a member of the opposition coalition, told the Associated Press.
Lafortune said a letter would be delivered to the OAS representative in Haiti, David Lee of Canada.
Meanwhile, Aristide made an emotional call for Haitians to stay in the country, instead of fleeing to Florida -- about 600 miles from Haiti -- so that they can vote in new elections.
"The criminals and terrorists went to the north, to Port-de-Paix, and burned private and public buses, killing people," Aristide said. "Unfortunately many brothers and sisters in Port-de-Paix will not come down to (the capital) Port-au-Prince; they will take to the sea, they will become boat people."
Most boat people want to go to the United States and many are picked up by the U.S. Coast Guard and sent home. In the past ten days, 62 Haitians have landed in Jamaica.
Neighboring Dominican Republic sent 1,200 extra troops to patrol its border with Haiti, military spokesman Col. Juan Julio Tejeda Madera said. He declined to provide the total number of troops at the 225-mile border, and said he did not expect a mass influx of refugees, "but we are ready."
The nearly three-week-old uprising in Haiti has left up to 70 people dead. Armed rebels have stormed at least a dozen towns, chasing away police and occupying areas mostly in the North.
The rebels have set up a base in Gonaives, Haiti's fourth-largest city 70 miles northwest of Port-au-Prince, and rebel leader Guy Philippe said he was setting up a second one in Cap-Haitien, the northern port and second-largest city that was seized Sunday.
Philippe told the Associated Press he does not want to install a military dictatorship but is seeking to re-establish the army that was disbanded by Aristide.
An attack on Port-au-Prince was unlikely Tuesday, as Philippe said his fighters had spent the night searching in vain for government forces.
In anticipation of a possible attack, militant supporters of Aristide have erected flaming barricades on roads throughout Port-au-Prince. And 50 U.S. Marines have been sent to protect the U.S. Embassy in the capital city.
Political discontent in the Caribbean country of 8 million people has been brewing since 2000, when Aristide's Lavalas Party took a majority of legislative seats in contested elections.
Opponents have staged demonstrations, which turned violent when a gang once loyal to Aristide revolted in Gonaives on Feb. 5.
Aristide has called for international help to better train and equip his police force, but his request has gone unanswered as countries, including the United States, accuse the Haitian president of politicizing the police force, ignoring corruption among officers and using the police and armed militants to crush dissent. Aristide has denied those charges.