"The act that the Zionists carried out in Tehran was a strategic mistake because it will cost them gravely," Bagheri said one day after attending an extraordinary session of the Organization of Islamic Cooperation (OIC) in Saudi Arabia.

Although Israel has not commented on Haniyeh's death, its responsibility for this act is widely confirmed.

Accordingly, Iran has vowed to retaliate, spiking tensions in the region already heightened by Israel's brutal assault on Gaza.

Bagheri accused Israel of seeking "to expand tension, war, and conflict to other countries," while asserting it was not in a position to fight Iran.

"The Zionists are in no position to start a war against the Islamic Republic of Iran," Bagheri said.

"They neither have the capacity nor the strength," he added.

Wednesday’s meeting of foreign ministers from the 57-member OIC resulted in a declaration holding Israel "fully responsible" for the "heinous" killing of Haniyeh, who was a major player in talks to end Israel's war on Gaza.

Israel's relentless bombardment and ground invasion have killed at least 39,699 people, mostly women and children, according to Gaza's Health Ministry.

Lebanon's Hezbollah has also pledged to retaliate for Haniyeh's killing and that of its military commander Fuad Shukr in an Israeli strike in Beirut hours earlier.

Bagheri said that Hezbollah and other Iran-allied groups in the region, including Yemen's Houthi rebels, had "similar goals" but would make independent decisions on how to pursue them.

"We have similar goals, but, in the field, the resistance movement acts based (on) its own... understanding of the situation and its interests," he said.

An Iranian operation targeting Israel would be "exactly in line with the preservation of the security and stabilization of the region," he noted.

Bagheri called on Washington and other countries to cease sending arms to Israel that could be used in its assault on Gaza and said economic aid and diplomatic relations with Israel should also be severed.

*This story was edited by Ahram Online.