People gather at the site of an Israeli airstrike that targeted Beirut’s southern suburbs neighbourhood of Haret Hreik as an Israeli strike in Lebanon's eastern Bekaa valley killed four people. AFP
The attack is the first on Beirut in nearly a month.
The source told AFP on condition of anonymity that "Malek Ballout, the operations commander in the Radwan force" was killed.
Lebanon's state-run National News Agency had reported that "Israeli warplanes launched an attack, targeting Ghobeiri in the southern suburbs of Beirut.
AFP journalists saw smoke rising from the targeted area.
The massive Israeli strikes across the country killed more than 350 people since the ceasefire took place.
Israeli strikes on Lebanon have since killed more than 2,700 people and displaced more than a 1,3 million, particularly from southern and eastern Lebanon and Beirut's southern suburbs.
Wednesday's attack came as US President Donald Trump said there was "a very good chance" of sealing a peace deal with Iran.
While a truce went into force on April 17, Israel has repeatedly bombed Lebanon, particularly the south, with Hezbollah retaliating by launching attacks on Israeli occupation troops.
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