Iran's Revolutionary Guard said a short-range projectile was behind the killing of Hamas political chief Ismail Haniyeh and accused the United States of supporting the attack which it blamed on Israel, state TV reported Saturday.

Wednesday's assassination has drawn fears of direct conflict between Tehran and its arch-enemy Israel in a region shaken by Israel's war in Gaza and a worsening conflict in Lebanon.

Revenge for the killing of the Hamas leader will be "severe and at an appropriate time, place, and manner," the Guards' statement added, blaming the "terrorist Zionist regime" of Israel for his death.

"The action was designed and carried out by the Zionist regime and supported by the U.S.," the statement read.

"The warmongering and terrorist Zionist regime will receive harsh punishment in the suitable time, place, and capacity," it added.

Iran and Hamas have accused Israel of carrying out the strike that killed Haniyeh hours after he attended the inauguration of Iran's new president.

Israeli officials have not claimed responsibility.

The statement by the elite Guards force also accused the "criminal U.S. government" of supporting the attack which Iranian media said was in a northern suburb of Tehran.

Haniyeh was buried Friday in Qatar, where he was based.

The televised statement said a rocket with a seven-kilogram (about 15-pound) warhead was used to target the residence of Hamas' political in the capital Tehran on Wednesday, adding it caused heavy devastation, but did not share details of the location.

Haniyeh was in Iran to attend the inauguration ceremony of the newly elected Iranian President Masoud Pezeshkian.

Israel had pledged to kill Haniyeh and other Hamas leaders over the group's Oct. 7 attack on southern Israel that sparked the war in Gaza.

The assassination has sparked fears of pushing the region into a wider conflict and forcing Iran and Israel into a direct confrontation if Iran retaliates.

In April, Iran launched hundreds of missiles and drones at Israel which the Jewish state said it intercepted 99% of. It came less than two weeks after a suspected Israeli strike in Syria killed two Iranian generals, marking the first time Iran has launched a direct military assault on Israel, despite decades of enmity dating back to the country's 1979 Islamic Revolution.

Iran does not recognize Israel and supports anti-Israeli terrorist groups like Hamas and Lebanese Hezbollah.

Information from The Associated Press was used to compile this report.