A projectile from fighting in the Syrian civil war struck the Golan Heights on Thursday and Israeli forces responded by attacking a Syrian army position, the military said.
In a statement, the military said it appeared the shooting from Syria was "errant fire" from battles between forces loyal to Syrian President Bashar al-Assad and rebels trying to topple him.
Such fighting, now in its fourth year, has often spilled over into Israeli-held parts of the Golan Heights, territory Israel captured from Syria in the 1967 Middle East war.
The military said that in response to the latest fire from the Syrian side of the frontier, "the IDF (Israel Defense Forces) targeted a Syrian army position, and hits were confirmed".
It did not say what type of attack Israel carried out. The Syrian Observatory for Human Rights said it was an air strike on a Syrian army base on the Golan. There were no immediate reports of casualties from either side.
Islamist fighters battling the Syrian army last week overran a U.N.-controlled crossing point on the "disengagement line" that has separated Israelis from Syrians on the Golan Heights since the 1973 Arab-Israeli war.
The fighters then turned against U.N. blue helmets from a peacekeeping force that has patrolled the zone since 1974. After 45 Fijians were captured on Thursday, 72 Filipinos were besieged by militants at two other locations for two days before the peacekeepers escaped.
The militants, believed to be part of an Al Qaeda-linked group known as Nusra Front, are still holding the 45 Fijian members of the United Nations' UNDOF Golan Heights force.
On Sunday, an Israeli Patriot missile shot down what the military described as a Syrian drone over the strategic plateau.