The Local Coordination Committees of Syria said the massacre in the village of Tremseh brought the nationwide death toll for Thursday to 189, CNN reported.
Syrian state television said the killings at Tremseh were carried out by "armed terrorist groups" that fired "indiscriminately."
"And after calls from the people of the village, the security forces clashed with the terrorist groups, arresting a number of them and confiscated their weapons," the state television report said.
The opposition said 12 people were killed in Damascus Thursday, in a neighborhood it said was under siege by government forces, including snipers shooting from rooftops.
Syrian government officials announced the country's ambassador to Iraq was fired Thursday, the day after he said he had defected.
The Syrian Foreign Ministry said in a statement Ambassador Nawaf Fares "has been relieved of his duties" and no longer had ties with the Syrian Embassy in Iraq, The New York Times reported.
Meanwhile, video posted online by a person thought to be a Syrian activist appear to show cluster-bomb remnants in an area near Hama, Human Rights Watch said Thursday.
An activist in the area said the region where the bomb remnants allegedly were found has been under heavy bombardment by Syrian forces during the past two weeks, the international human rights organization said in a release.
The videos, posted Tuesday, appear to show Soviet-produced unexploded submunitions and a bomb canister. The videos have not been authenticated.
"These videos show identifiable cluster bombs and submunitions," said Steve Goose, HRW arms division director. "If confirmed, this would be the first documented use of these highly dangerous weapons by the Syrian armed forces during the conflict."
Human Rights Watch said it hasn't yet determined whether civilians in Jabel Shahshabu area were wounded or killed by cluster munitions.
The rights organization said Syria hasn't been known to use cluster munitions in the past and it isn't believed to produce them. However, the country has imported cluster munitions previously and has a stockpile.
The announcement concerning Fares, reported by the official Syrian Arab News Agency, came after the diplomat said in a statement Wednesday he had defected and called on "all honest members of this party [the Baath Party] to follow my path because the regime has turned it to an instrument to kill people and their aspiration to freedom."
In its statement, the Foreign Ministry said Fares "made press statements that contradict the duties of his position of defending the country's stances and issues, which demands legal and behavioral accountability."
The ministry accused him of leaving the embassy in Baghdad without permission. Fares issued his statement from an undisclosed location, the Times said.
Last week, senior army officer Brig. Gen. Manaf Tlas, who commanded a unit of the elite Republican Guard, fled Syria to Turkey.
Western nations are pressing the United Nations to threaten Syria with sanctions as it considers renewing the mandate for its 300-member observer mission in Syria, due to expire July 20, the BBC said. The mission, part of an all-but-ignored peace plan brokered by U.N.-Arab League envoy Kofi Annan, was to observe compliance with a cease-fire but suspended its work a month ago because both the Syrian government and its opponents were ignoring the plan, and escalating violence made the work too dangerous.
Annan asked the U.N. Security Council Wednesday to threaten both the Syrian government and the rebels with consequences for failure to comply.
Already circulating is a draft resolution threatening Damascus with sanctions within 10 days if government forces don't stop using heavy weapons and fail to pull back troops from towns and cities, the BBC said.
Britain's ambassador to the United Nations, Mark Lyall Grant, told reporters Britain, France, the United States and Germany would propose making compliance with the cease-fire mandatory under Chapter 7 of the U.N. charter.
Last week, more than 100 countries urged the Security Council to invoke Article 41 of the charter, which calls for international involvement short of military intervention.
Russia and China, both permanent members of the Security Council with heavy ties to Syria, have blocked previous attempts to impose tougher measures. Russia, however, indicated it would support a renewal of the mission's mandate.
Syrian opposition groups estimate 12,000 to 14,000 people have died since the uprising against President Bashar Assad began in March 2011.