The attack yesterday pushed the death toll for two days of violence across Syria to more than 200, and was one of the deadliest single events of the entire nine-month uprising against President Bashar Assad's authoritarian rule.
The White House reacted by renewing its call for Assad to step down, saying his regime does not deserve to rule. The offensive targeted the village of Kfar Owaid, about 49 kilometres from the northern border with Turkey.
It is part of the rugged mountainous region of Jabal al-Zawiyah, which has been the scene of clashes between troops and army defectors and intense anti-government protests for weeks. Syrian troops began attacking the region on Saturday, residents said.
"It was an organised massacre," said Rami Abdul-Rahman, head of the British-based activist group Syrian Observatory for Human Rights. "The troops surrounded people then killed them."
Syrian officials have not commented on the allegations. The White House said Assad's regime has no credibility and has "flagrantly violated" its commitment to end violence. The statement said the Obama administration is deeply disturbed by continued reports of government-backed violence against the Syrian people.