JERUSALEM - Israel shelled Syrian fighters after gunfire from their civil war spilled over to the Israel-controlled Golan Heights, the military said Sunday as the conflict appeared to inch closer to the Jewish state.

The civil war in Syria has renewed tensions in the Golan Heights, a strategic plateau that Israel captured from Syria in the 1967 war. Despite constant hostility between the two countries, Syria has been careful to keep the border quiet since the 1973 Mideast war.

But Syrian shells have exploded inside the Israel-held Golan Heights several times in recent weeks, damaging apple orchards, sparking fires and spreading some panic but causing no injuries.

In recent days, Israel responded to what appeared to be stray mortar shells exploding in Israel-held territory with artillery fire of its own. On Sunday, an Israeli military spokesman said soldiers fired toward the source of gunfire late Saturday night.

Though the two nations have been bitter enemies, Israel is concerned that if the Assad regime is toppled, Syria could fall into the hands of Islamic extremists.

While it is widely believed that Assad does not want to pick a fight with Israel, some in Israel warn that if his situation becomes desperate, the embattled Syrian leader might try to draw Israel into the fighting as a distraction.

Fighting has raged nationwide over the weekend, killing at least 108 people on Saturday alone, according to activists.

In Tehran, Iranian Foreign Minister Ali Akbar Salehi warned that providing opposition groups with heavy arms could put the entire region at risk of "organized terrorism." He was responding to a move in Europe to cancel an arms embargo.

He said that arming Assad's opponents, as Damascus accuses Qatar and Saudi Arabia of doing, violates international law and principles of nonintervention in domestic affairs.

More than 36,000 people have been killed since the Syrian uprising began in March 2011.