The latest crackdown by Syrian forces comes despite the EU slapping Damascus with the embargo, in a move criticised by Syria's long-time ally Russia.
"Two men were killed and five wounded in Maarrat in Idlib region during an incursion by tanks and 50 buses carrying members of the security forces," said the Local Co-ordination Committees (LCC), which have activists on the ground.
On Friday, widespread demonstrations were repressed by security forces, who killed at least 21 people, the Britain-based Syrian Observatory for Human Rights said in a statement.
Nine people were killed in the Damascus area, nine in the central province of Homs and three in Deir Ezzor, eastern Syria, the Observatory said.
The victims, including a 16-year-old girl and an elderly woman, were killed as security forces opened fire to disperse thousands of anti-regime protesters out on the streets.
"We are ready to die as martyrs by the millions," activists wrote on their Facebook page, Syrian Revolution, ahead of the protests. The LCC said protests would carry on "every day until the fall of the regime".
According to the UN, more than 2 200 people have been killed in Syria since the protests began on March 15.
An EU oil embargo against Syria went into effect on Saturday a day after its adoption by the 27-nation bloc to punish the government for its brutal suppression of the protest movement.
The EU also expanded its list of pro-government figures and firms targeted by an assets freeze and travel ban, adding four businessmen accused of bankrolling the regime and three firms, diplomats said.
The oil embargo will deprive Assad's regime of a vital source of cash as the EU buys 95% of Syria's crude exports.
Russian Foreign Minister Sergei Lavrov criticised the embargo, Russia's Interfax news agency reported.
"We have always said that unilateral sanctions will do no good. This destroys a partnership approach to any crisis," Lavrov was quoted as telling journalists at a regional summit in Dushanbe.
"We are against unilateral sanctions. Sanctions rarely solve anything in general," he added.