Iran said on Monday that Israel had lost its power to deter and that the strategic balance in the region had shifted against it, following attacks by the Lebanese armed group Hezbollah.

Hezbollah launched hundreds of rockets and drones at Israel early on Sunday, as Israel's military said it had struck Lebanon with around 100 jets to thwart a larger attack, in one of the biggest clashes in more than 10 months of border warfare.

"Despite the comprehensive support of states like the United States, Israel could not predict the time and place of a limited and managed response by the resistance. Israel has lost its deterrence power," Iranian foreign ministry spokesman Nasser Kanaani wrote on X.

Kanaani added that Israel "now has to defend itself within its occupied territories" and that "strategic balances have undergone fundamental changes" to the detriment of Israel.

Any major spillover in the fighting, which began in parallel with the war in Gaza, risks morphing into a regional conflagration drawing in Iran, Hezbollah's backer, and the United States, Israel's main ally.

Hezbollah leader Sayyed Hassan Nasrallah said the group's barrage, a reprisal for the assassination of senior commander Fuad Shukr last month, had been completed "as planned".

With three deaths confirmed in Lebanon and one in Israel after Sunday's exchanges, both sides indicated they were happy to avoid further escalation for now, but warned that there could be more strikes to come.