Police were sent into the northern city two days after the rebels attacked the main police station in a battle which left 11 dead.
"It is with sorrow that we announce 14 dead among the police," rebel leader Etienne Winter told Haitian radio stations on Saturday.
He said his group had left the police station but still controlled Gonaives. There was however no official toll.
The city of about 200,000 people, the fourth largest in the Caribbean republic, was virtually deserted when the police reinforcements arrived.
Winter announced the area around Gonaives had been declared "an independent zone."
"We are going to liberate other districts in the region," he added.
Another police station in nearby Trou du Nord was taken over by armed men on Friday. Homes of supporters of the Haitian President Jean-Bertrand Aristide were also attacked.
Haiti in recent months has been swept by political turmoil with opponents of Aristide calling for his resignation.
There has been violence between opponents and supporters of Aristide in Gonaives since September, which has left more than 60 people dead.
The siege at Gonaives is however the most serious challenge to the president till date.
Meanwhile, Aristide has vowed that those responsible for the siege "will be arrested and judged according to law."
He also said he would stay on until his current term ends in 2006.