"The glorious path of the leader of the resistance, Hassan Nasrallah, will continue and his sacred goal will be realised in the liberation of Quds (Jerusalem), God willing," foreign ministry spokesman Nasser Kanani said in a post on social media X, mourning Nasrallah's death.

Lebanon's Hezbollah group, armed and financed by Iran, on Saturday confirmed Nasrallah had been killed, after Israel said it had "eliminated" him in an air strike a day earlier.

The statement confirmed he was killed with other group members "following the treacherous Zionist strike on the southern suburbs" of Beirut.

Iranian vice president Mohammad Javad Zarif also expressed his condolences, praising Nasrallah as a "symbol of the fight against oppression."

Hezbollah is listed as terrorist group by the United States.

A black flag for mourning was hoisted at the Shiite Islam holy Imam Reza shrine in Iran's northeastern city Mashhad, according to the local Tasnim news agency.

Mourners gathered there, waving yellow Hezbollah banners, along with Iranian flags as they chanted, "Death to Israel," state TV showed.

Lebanon's health ministry gave a preliminary toll of six dead and 91 wounded from the latest strikes on Beirut's densely populated southern suburbs since Friday, the fiercest to hit Hezbollah's stronghold since Israel and the group last went to war in 2006.

Earlier on Saturday, Iran's supreme leader Ayatollah Ali Khamenei condemned what he called an Israeli "massacre" in Lebanon and lambasted the "shortsighted" Israeli policy.