U.N. troops, stationed in Haiti since Jean-Bertrand Aristide was ousted as president in a bloody rebellion in 2004, fired tear gas and rubber bullets on several occasions to disperse protesters.
Many Haitians seemed to welcome the ouster of Alexis.
"When he was prime minister, he did nothing to lower the high cost of living. I hope things will change with a new prime minister," said Jean Pierre Jean-Baptiste, 29, an electrician.
Disturbances over high food prices have broken out in several poor countries, primarily in Africa. Record oil prices, rising demand for food in Asia, the use of farmland and crops for biofuels and other factors such as market speculation have pushed up food prices worldwide.
The World Food Program and other aid agencies have issued urgent appeals for donations. Brazil, which heads the U.N. peacekeeping force in Haiti, on Friday sent an air force cargo plane carrying 14 metric tonnes of food.
"The situation is difficult everywhere around the world, everyone has to make a sacrifice," Preval said on Saturday as he announced the plan to cut rice prices in a room adorned with crystal chandeliers and thick drapes at the National Palace.
'IT'S UNJUST'
Asked before the Senate vote how he viewed the criticism of Alexis, he said: "I think it's unjust because the government is not responsible for the rapid acceleration of prices on the international markets. The government has dealt with the crisis to the best of its ability."
Preval reiterated that Haiti could not afford to cut taxes on food because it needed the revenue to pay for longer-term projects that create jobs and boost agriculture.
It was unclear whether the price cut would satisfy protesters.
"It has not been lowered enough," said a young man who identified himself only as Givens. "If they don't further lower the price I think people are going to protest more. There will be problems, more unrest. Even the National Palace could be set on fire because we are in trouble."
Sen. Youri Latortue, a nephew of a former prime minister and leader of Saturday's vote, said Alexis had failed to ramp up food production, protect people against crime and heed calls to establish a new national security force.
"He does not have the leadership to lead the government," Latortue said.
