Hezbollah launched hundreds of missiles and drones at Israel in retaliation for the assassination of a senior commander in Beirut last month.
The violence on August 25 was one of the largest shootings since the conflict began between Israel and Hezbollah in parallel with the start of Israel's war against Hamas in Gaza.
In a statement, the Israeli military said that about 100 Israeli warplanes attacked more than 40 Hezbollah launch sites in southern Lebanon right before the group's attack.
Hezbollah also claimed to have launched drones and more than 320 Katyusha missiles towards Israel and attacked 11 military targets. Hezbollah said it had completed the "first phase" of the attack in response to the assassination of Fuad Shukr, a senior Israeli commander, last month in Beirut.
Hezollhah denied Israel's allegations of the coordinated attacks but said in a statement that their military operations were successfully completed within the day.
Israeli Prime Minister Benjamin Netanyahu chaired an emergency security cabinet meeting at 7 a.m. local time.
We are determined to do everything we can to protect the country, return the people of the North home safely and continue to maintain a simple rule: Whoever harms us - we will harm that person, Netanyahu said in a statement.
Israeli Foreign Minister Katz said Israel would react to developments on the ground but not seek a full-scale war.
The Israeli military spokesman said that most of the Israeli strikes were aimed at targets in southern Lebanon, but the army was ready to attack anyplace with a threat.
Israel has declared a state of emergency and flights to and from Ben Gurion airport in Tel Aviv have been suspended for about 90 minutes, but airport authorities said normal operations are expected to resume at 7am.
