Israeli Defence Minister Yoav Gallant vowed to "hit the enemy hard" a day after rocket fire from Lebanon killed 12 minors in Majdal Shams, again raisings fears that the war in Gaza will spread.
Israel blamed Lebanon's Hezbollah movement for firing a Falaq-1 Iranian rocket but the Iran-backed group -- which has regularly targeted Israeli military positions -- said it had "no connection" to the incident.
"Hezbollah has evacuated some positions in the south and in the Bekaa valley that it thinks could be a target for Israel," the source close to the group told AFP, requesting anonymity as they were not authorised to speak to the media.
Hezbollah has a strong presence in east Lebanon's Bekaa valley, which borders Syria, and in south Lebanon, where it has been launching near daily attacks on Israeli positions since October in support of ally Hamas.
The cross-border exchanges of fire have largely been limited to the border area, but Israel has repeatedly struck deep inside Lebanon, including overnight.
Hezbollah is also deployed in Syria, where for years it has been fighting in support of President Bashar al-Assad in his country's civil war.
The Syrian Observatory for Human Rights, a war monitor, said pro-Iran groups and Hezbollah-affiliated fighters have "evacuated their positions" south of the capital and in the Damascus countryside, as well as in parts of the Syrian-controlled Golan Heights, in anticipation of "potential Israeli airstrikes".
Hezbollah had already abandoned positions in Syria in early June after Israeli raids, according to the Britain-based Observatory, which relies on a network of sources on the ground.
Flights rescheduled
Since Syria's civil war erupted in 2011, Israel has carried out hundreds of strikes in the country, mainly targeting army positions and Iran-backed fighters, including from Hezbollah.
The raids also seek to cut off Hezbollah supply routes to Lebanon.
Israeli authorities rarely comment on individual strikes in Syria, but have repeatedly said they will not allow arch-enemy Iran to expand its presence there.
Israel's raids on Syria intensified after Palestinian militant group Hamas's October 7 attack on Israel sparked war in the Gaza Strip, then eased after an April 1 strike blamed on Israel hit the Iranian consular building in Damascus.
That strike prompted Iran to launch a first-ever direct missile and drone attack against Israel on April 13-14, sending regional tensions skyrocketing.
Lebanon's Middle East Airlines said in a statement that it had rescheduled a number of flights on Sunday and Monday, citing "technical reasons related to the distribution of (aircraft) insurance risks".
In October, the carrier said it was relocating some planes abroad in light of regional developments.
During a 2006 war between Israel and Hezbollah, Israel struck Beirut airport, Lebanon's only international facility.
The cross-border violence since October has killed at least 527 people in Lebanon according to an AFP tally, most of them fighters but also including 104 civilians.
On the Israeli side, 22 soldiers and 24 civilians have been killed, according to Israeli authorities.
Israeli strikes have killed at least 25 Hezbollah fighters in Syria since the Gaza war erupted, according to an AFP tally.