"We warn the leaders of the occupying regime that the unjust bloodshed... especially of Hezbollah's secretary general, martyr Seyyed Hassan Nasrallah, will bring about their destruction," Iran's ISNA news agency quoted Aref as saying.

Lebanon's Hezbollah group, armed and financed by Iran, confirmed on Saturday that Nasrallah had been killed, after Israel said it had "eliminated" him in an air strike on Hezbollah's bastion in Beirut's southern suburbs the previous day.

Aref said that Iran will "stand by the Islamic resistance".

President Masoud Pezeshkian offered his condolences over Nasrallah's death and accused the United States of "complicity" in his killing.

A black flag of mourning was hoisted at the Imam Reza shrine in Iran's second city of Mashhad, the Tasnim news agency reported.

Mourners gathered waving yellow Hezbollah flags and chanting: "Death to Israel", state TV footage showed.