More than 30 people have reportedly been killed in Syrian government air strikes in Latakia province and the northern city of Raqa.
Seven children were among at least 13 civilians who died in an air raid on Raqa, the only provincial capital in rebel hands, according to the Syrian Observatory for Human Rights monitoring group.
It said the raid was apparently aimed at positions of the jihadist Islamic State of Iraq and the Levant (ISIS) which largely controls the city.
ISIS has been the dominant force in the city since its capture by rebels in March.
Residents have held several protests against the policies of ISIS which follows an extremist line of Islam, according to the Observatory.
Government forces attack Raqa, the only provincial capital in rebel handsAn Italian Jesuit priest and activist, Paolo Dall'Oglio, who hoped to negotiate with ISIS in Raqa, went missing in the city at the start of August.
In the coastal Latakia province of northwest Syria, at least 20 people were killed in several air strikes on the Sunni rebel town of Salma, the Observatory said.
At least six of those killed were Syrian rebel fighters while four were foreign volunteers, said Rami Abdel Rahman, who heads the Observatory.
Latakia province is a stronghold of the Alawite minority of Syrian President Bashar al Assad, apart from rebel-held pockets.
Islamist rebel forces have captured about 10 Alawite villages in Jabal al-Akrad, a mountainous area of the province.
The army has hit back, sparking fierce fighting that has left dozens dead on both sides.
Smoke rises in the town of SalmaRebels have kidnapped a leading Alawite cleric, Sheikh Badreddine Ghazal, said the Observatory, which relies on a network of activists on the ground and medics for its information.
In Damascus, a car bomb ripped through the Shaghur district of the capital late on Saturday, wounding several people, three of them children.
In Aleppo province, further east, government troops stormed a village overnight, killing 12 people, the Observatory said.
Al-Nusra Front jihadists and other rebel fighters in the eastern city of Deir Ezzor seized control of the offices of Syria's ruling Baath party in the Howeika district, sparking regime bombardment, the Observatory said.
More than 100,000 people have been killed in the past 29 months of conflict.