Israel lodged a complaint with United Nations monitors on Saturday after three Syrian tanks entered the demilitarised Golan Heights zone that separates the two countries, a military spokeswoman said.
The spokeswoman told AFP the incident occurred on Saturday morning, at some distance from Israeli positions on the strategic plateau.
Israeli media said the tanks entered the village of Beer Ajam, southeast of Quneitra, to fight rebel forces.
Israeli public radio said the military raised its state of alert in the area as a result, but the spokeswoman refused to comment.
Syria remains formally at war with Israel, which captured part of the Golan Heights in the 1967 Middle East war and annexed it in 1981 in a move the international community does not recognise.
Since a 1974 disengagement agreement between the two countries, a 1,200-strong unarmed UN force has patrolled a buffer zone on the heights.
In July, Israel complained to the UN after Syrian soldiers crossed into the zone in violation of the agreement.