The Israeli attack targeting Haytham Ali Tabatabai was the first strike on Beirut in more than five months and fueled fears that a wider war could be brewing.
U.S., Ukrainian and European officials are due to meet in Switzerland on Sunday for talks on the contentious American-Russian peace plan put to Kyiv this week.
Israel said the strikes were in response to militant gunfire, which Hamas rejected as fabricated "to evade the agreement and return to the war of extermination."
