Haiti: Clashes in protest over the high cost of fuel
Several people were injured as police moved in to clear roadblocks set up in the capital, Port-au-Prince.
Protest organisers said that drivers who ventured into the city centre during the two-day protest would be putting their lives at risk.
Haiti has seen months of protests against President Michel Martelly over delayed elections.
"Because of the price of fuel, the cost of living is going up," said Ralph La Croix, a Port-au-Prince resident.
"If the government could cut the price of fuel so it was lower, the population would live better," he told the Reuters news agency.
Petrol and diesel prices have been reduced by the government recently, but protesters want a 50% cut, reflecting the drop in international oil prices over the past six months.
The price of a gallon of petrol in Haiti initially dropped by about 25 cents to $4.50 (£3) and further cuts will reduce that price to about $4. Diesel prices were cut down by 20 cents to $3.55 (£2.30) and will now go down to $3.30.
The government said the protests would damage the country's troubled economy and create "devastating consequences for the most vulnerably people in our population," a government statement said.
Prime Minister Evans Paul made an appeal for calm.
The government "cannot lower the price of petrol. It's not that we do not want to, it's because we are not able to," he said.
Protesters say they will set up new roadblocks in Port-au-Prince on Tuesday.
Mr Martelly began ruling by decree last month after the parliament's term expired.
He has since reached an agreement with the opposition to form a new government and hold general and local elections, which are three years overdue.
But discontent continues in the poorest nation in the Western Hemisphere, struck by a powerful earthquake in 2010 which devastated much of Port-au-Prince.