Israel returned fire after one of its military vehicles was hit by shots from Syria, Israel’s defence forces say. Media reports say no-one was hurt.
Syria says it destroyed an Israeli vehicle which it says crossed the ceasefire line into territory its forces control.
Syria and Israel have traded fire a number of times in recent weeks.
The Israeli military said its troops “returned precise fire” after the vehicle was hit.
A statement from the Syrian army said it had “destroyed an Israeli vehicle with everything that it had in it”. The statement said the vehicle was shot after it crossed the ceasefire line and headed towards the rebel-held village of Bir Ajam.
It warned that any attempts to violate its sovereignty “will be met with immediate and firm retaliation”.
Syrian President Bashar al-Assad has previously accused Israel of aiding the rebels, but has not provided substantive evidence.
Syrian gunfire has hit the Israeli-occupied Golan Heights in two previous incidents this week, without causing injury. There have been sporadic exchanges of fire between the two sides in recent months.
The difference this time is that the Syrian regime, which did not comment on the previous reported incidents, have made a big issue of this one, and cast it in quite a different light, says the BBC’s Jim Muir in Beirut.
It has used the event to highlight what it calls the close co-operation between Israel and the Syrian rebels – whose wounded in that area are in fact reported to be being treated in Israeli medical facilities, he says.
By warning of an “immediate and firm” response to any future “breaches” it also hinted at the kind of regional flare-up that is increasingly worrying the international community as it sees the Syrian crisis deepening, our correspondent adds
Tensions between Israel and Syria have soared this year, with Israel allegedly carrying out three air strikes on Syria to stop the transfer of advanced weapons to the militant Islamist movement Hezbollah in Lebanon.
Syrian shells have hit Israeli positions on the Golan Heights, though it is unclear whether they were aimed at rebels in border areas, and Israel has returned fire.
Syria and Israel have been in a state of war since 1948 but the border had been relatively calm in recent years.
Israel has occupied the Golan Heights since the 1967 war. It annexed the territory in 1981, in a move that has not been recognised by the international community.