The Israeli military said the strike had "eliminated" Fuad Shukr, a top Hezbollah commander it blamed for carrying out a weekend rocket attack on the Israeli-annexed Golan Heights that killed 12 children.
The raid on the Beirut suburb, an overcrowded residential area that is also a Hezbollah bastion, killed siblings Amira and Hassan Fadlallah as well as two women and injured dozens of civilians, according to Lebanon's health ministry.
"I feel very angry because the... lives of our children are becoming very cheap," said Aya Ahmed, 38, a friend of the two killed children's mother.
The Iran-backed group said Shukr was in the targeted building but that his fate remained unknown.
An AFP photographer at the scene on Tuesday night saw an eight-storey building that had partially collapsed in the strike, while ambulances struggled through crowds and rescue workers combed through the rubble of the building for survivors.
"Every mother now is thinking: I could lose my children at any moment because the Israelis have a license to kill," said Ahmed.
At the procession in southern Beirut, Hezbollah-affiliated scouts carried the two children's coffins, draped in the youth group's white flag.
Other mourners carried photographs of the two dead siblings while some held up Hezbollah's flag.
"I feel sorry for the children, but... even if the jets are above our heads and striking we will be fighting," Walida Othman, 45, told AFP defiantly.
Lebanon's Hezbollah group has been exchanging near-daily fire with Israel since its Palestinian ally Hamas attacked Israel on October 7, sparking war in Gaza.
On the Lebanese side, the violence has killed at least 535 people, most of them fighters but also including 109 civilians, according to an AFP tally.
At least 22 soldiers and 25 civilians have been killed on the Israeli side, including in the Golan Heights, according to army figures.
