The strike, the first on the outskirts of the Lebanese capital in months, targeted Hezbollah's acting chief of staff, Ali Tabtabai, the military said in a statement.
Israel's strike crossed a "red line", Hezbollah official Mahmoud Qmati said. Hezbollah's leadership would decide on whether and how the group would respond, he added.
The United States imposed sanctions on Tabtabai in 2016, identifying him as a key Hezbollah leader and offering a reward of up to 5 million USD for information on him.
The Israeli military statement said Tabtabai "commanded most of Hezbollah's units and worked hard to restore them to readiness for war with Israel".
