The official spoke on condition of anonymity because he was not authorized to give official statements.
There was no immediate comment from Israel, which almost never confirms or denies airstrikes in Syria. Such strikes have become more frequent recently, amid soaring tensions between regional archenemies Israel and Iran.
Iran has vowed to retaliate to recent Israeli strikes in Syria targeting Iranian outposts in the country. They include an attack last month on Syria's T4 air base in Homs province that killed seven Iranian military personnel, for which Tehran has vowed to retaliate. On April 30, Israel was said to have struck government outposts in northern Syria, killing more than a dozen pro-government fighters, many of them Iranians.
Israel's military, however, said Tuesday its forces were on high alert near its border with Syria after spotting Iranian activity and was urging civilians in the Golan Heights near Syria to prepare bomb shelters.
Later, the Israeli military said in a statement it had called up some reservists but did not elaborate.
The military directive Tuesday came "following the identification of irregular activity of Iranian forces in Syria." It said defense systems have been deployed.
The military said it is prepared for "various scenarios" and warned "any aggression against Israel will be met with a severe response."
Israel has warned it will not tolerate Tehran establishing itself militarily on its doorstep in Syria.
- AP