The Britain-based Syrian Observatory for Human Rights said troops and security agents had attacked villages in the region,
"Four soldiers were killed and a number of civilians killed or wounded in fighting this morning between the Syrian army and deserters in Jabal al-Zawiya" in Idlib province near the Turkish border, it said.
Security forces have been trying for months to bring an end to a popular uprising which has seen hundreds of thousands marching in major cities against the regime of President Bashar al-Assad.
The United Nations estimates that in the crackdown more than 2,700 people have been killed since mid-March.
Syria maintains that the regime's opponents are armed gangs and terrorists trying to sow chaos in the country.
A resolution put to the Security Council was vetoed this week by Russia and China, a move denounced by several western countries, including the United States.
Damascus welcomed the Chinese-Russian vetoes as "historic."