As lawmakers met inside the parliament building, protestors carried signs reading "No to corruption!" and "Parliament -- stand with the people, say no to raising prices!"
"No to rising prices, people are starving to death," another read.
The demonstration appeared to be tolerated by Syria's authorities, with about a dozen riot police stationed near parliament allowing the protest to go ahead.
In a letter to parliament, a copy of which was obtained by AFP, the demonstrators called on lawmakers to "cancel their decision to raise the prices of petroleum products."
"The strike will continue on a daily basis until we get a response and the protest's goal is achieved," the letter said.
On Thursday Syria's government ordered the price of a litre of petrol increased from 160 to 225 Syrian pounds (about 90 US cents), state news agency SANA said, with similar increases for cooking gas and diesel.
"We called for this strike to protest the rising prices of petroleum products which will in turn negatively affect all other prices," said Firas Nadim, a member of a consumer protection group that organised the demonstration.
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"The government had been trying to improve the quality of life for the average citizen, but now they are trying to starve him," Nadim told AFP.
Lawmakers were meeting for their second session since being elected in April.
SANA quoted parliamentarians as stressing "the need to postpone the official decision on amending the prices of oil products and to study the extent of its effect on the quality of life."
Oil production has slumped in Syria since the beginning of the country's five-year civil war, which has killed more than 280,000 people, displaced millions and devastated the economy.
While residents of Damascus have remained relatively insulated from the violence, they have suffered from inflation and severe unemployment.
Damascus witnessed some anti-government demonstrations in 2011, when Syria's conflict first erupted.
But as violence increased throughout the country, street protests in the capital became increasingly rare.
Sunday's gathering followed expressions of frustration on social media, in some cases even from supporters of President Bashar al-Assad, over the government's economic policies.