Israeli aircraft struck Syrian army artillery positions early on Wednesday, the military said, in retaliation for rockets launched at the Israel-occupied Golan Heights a day earlier.
The strike came amid rising frontier tension 10 days after an Israeli air strike in Syria killed an Iranian general and several Lebanese Hezbollah guerrillas.
The air strike on targets in areas under the control of Syrian President Bashar al-Assad sent a clear message, Israeli Defence Minister Moshe Yaalon said in a statement.
"We will not tolerate any firing towards Israeli territory or violation of our sovereignty and we will respond forcefully and with determination," Yaalon added.
On Tuesday, at least two rockets from Syria hit the Golan Heights and Israel responded with artillery fire, the army said. That incident forced Israel to evacuate its Mt. Hermon ski resort on the Golan Heights, although a resort official said it had reopened for business on Wednesday.
There was no immediate claim of responsibility for the rocket fire and no casualties were reported.
In the Israeli air strike on a Hezbollah convoy near the Golan Heights on Jan. 18, an Iranian Revolutionary Guard general, Mohammed Allahdadi, was killed along with a Hezbollah commander and the son of the group's late military leader, Imad Moughniyeh.
Both Hezbollah, which is backed by Iran and fought a 34-day war with Israel in 2006, and the Revolutionary Guards vowed to avenge the deaths.
Since that air strike, troops and civilians in northern Israel and the Golan Heights have been on heightened alert and Israel has deployed an Iron Dome rocket interceptor unit near the Syrian border.
Israel captured the Golan from Syria in the 1967 Middle East war. Mortar shells and rockets have struck the Heights numerous times during Syria's nearly four-year-old civil war.
In Washington, State Department spokeswoman Jen Psaki told reporters U.S. officials "do not want to see an escalation of the situation." Psaki said the United States calls "upon all parties to avoid any action that would jeopardise the long-held ceasefire between Israel and Syria."
"We support Israel's legitimate right to self defence and have been clear about our concerns over the regional instability caused by the crisis in Syria," Psaki added.
Iran has told the United States last week's air strike crossed "red lines" and it will respond, IRNA news agency on Tuesday quoted a senior official as saying.
