The Lebanese-based militant group Hezbollah says it was behind the bomb blast that struck an Israeli military convoy along the Israeli-Lebanese border Monday.
Israel confirms there was a blast and says it retaliated by shelling Hezbollah targets in southern Lebanon.
The Israelis gave no details, and neither side would confirm if there were any casualties.
The roadside bomb blew up in the long-disputed Shebaa Farms area.
Hezbollah claims the blast was to avenge the death of Samir Kantar, one of its top militants killed in an airstrike near Damascus last month.
Hezbollah accuses Israel of assassinating Kantar. The Israelis refuse to confirm or deny involvement.
Kantar spent nearly 30 years in an Israeli prison for terrorism. He was freed in 2008 and later fled to Syria to fight for President Bashar al-Assad.