Sixteen members of the same family were among 22 people killed in raids late Saturday and Sunday on the town of Talbisseh, the Syrian Observatory for Human Rights said, updating an earlier toll.
They included 12 children and three women, said the Britain-based monitoring group which has a wide network of sources inside Syria.
Talbisseh was one of Syria's first areas to fall under rebel government control, after the 2011 outbreak of a revolt against President Bashar al-Assad.
In the Waer district on the outskirts of Homs -- the only area of Syria's third city still in rebel hands -- air strikes late on Sunday killed seven people, including a child, the Observatory said.
Activists say army bombing of densely-populated Waer has escalated in recent weeks, marring hopes of a truce similar to those reached in other parts of the country.
The escalation came after 47 children were killed in an October 1 suicide attack at a school in a government-held area of Homs city.
"The new head of the branch has launched a barbaric campaign against the neighbourhood... Where the humanitarian situation is deplorable," he said.
Homs was once dubbed "the capital of the revolution" against Assad.
But government forces retook control of the whole of the rest of the city in May when rebel fighters withdrew from central districts under a UN-brokered deal that ended a punishing two-year siege.
Elsewhere in the war-ravaged country, rebel fire Sunday on a school in the northern city of Aleppo killed a child and a man, and wounded 26 other people.
Both sides in the war have been accused by rights groups of launching attacks in Aleppo that amount to war crimes, because they fail to discriminate between civilian and military targets.