Britain-based Syrian Observatory for Human Rights reported that 30 people were also wounded in the assaults by Al-Qaeda's former Syria branch, Hayat Tahrir al Sham, and its ally Hurras al Deen.
Attacks by two militant groups killed at least 17 Syrian regime troops and militiamen in the northern province of Aleppo early on Saturday, a war monitor said.
Thirty others were wounded in the assaults by Al Qaeda's former Syria branch, Hayat Tahrir al Sham (HTS), and its ally Hurras al Deen, which remains affiliated to the global militant network, the Britain-based Syrian Observatory for Human Rights said.
The attacks in the southern and southwestern countryside of Aleppo province were launched shortly after midnight and triggered clashes that continued until dawn, Observatory head Rami Abdel Rahman said.
He said the fighting subsided after Russian aircraft struck opposition's positions in the area, prompting the fighters to pull back.
Eight militants were killed, he added.
Russia aircraft also carried out strikes in neighbouring Hama province early on Saturday, killing five civilians, the Observatory said.
On Friday, Russian strikes killed 10 civilians in Idlib province, the hub of territory held by the militants of HTS in northwestern Syria.
Russia and Turkey in September inked a buffer zone deal to avert a massive government offensive on the Idlib region, but the deal has never been implemented.
The region of some three million people has come under increasing bombardment since HTS took full control of it in January.
The latest Russian air raids came after two days of talks on the Syrian conflict between Turkey, Russia and fellow government backer Iran in Kazakhstan earlier this week.
The three governments expressed concern over the growing power of HTS in Idlib and parts of adjacent provinces, and determination to cooperate to eliminate the militant group.
The civil war in Syria has killed more than 370,000 people and displaced millions since it began with the bloody repression of anti-government protests in 2011.
Full-scale assault on Idlib "not expedient" –Putin
A full-scale assault against militants in Syria's Idlib province "is not expedient now" and civilians' security needs to be taken into account, Russian President Vladimir Putin said on Saturday.
Speaking in Beijing, Putin said Russia would work with the Syrian opposition to finalise the make-up of a constitutional committee, part of efforts to secure a political settlement of the conflict.
Russia has helped forces loyal to Syrian regime leader Bashar al Assad take back most of the country in the eight-year-old war but fighting continues.