Ali Bagheri, Iran's acting foreign minister, told AFP that Israel had committed "a strategic mistake" by killing Hamas's political leader Ismail Haniyeh in Tehran last week -- hours after the assassination in Beirut of Hezbollah's military chief.
Although Israel has not admitted to killing Haniyeh, Iran and its allies have vowed to retaliate, setting the region on edge as the Gaza war raged on into its 11th month.
Israel seeks "to expand tension, war and conflict to other countries", but has neither "the capacity nor the strength" to fight Iran, Bagheri said.
Prime Minister Benjamin Netanyahu, speaking at a military base on Wednesday, said Israel was "prepared both defensively and offensively" and "determined" to defend itself.
Haniyeh's group named a successor on Wednesday -- Yahya Sinwar, who Israel says had a key role in planning Hamas's unprecedented October 7 attack that sparked the Gaza war.
Analysts believe Sinwar -- Hamas's leader in the Gaza Strip since 2017 -- has been both more reluctant to agree to a ceasefire and closer to Tehran than Haniyeh, who lived in Qatar.
On the ground in Gaza, fighting continued on Thursday with the Israeli military issuing its latest evacuation order and rescuers and medics reporting at least 13 killed in strikes.