Tehran, Iran -- Iran on Tuesday rejected Western calls to stand down its threat to retaliate against Israel for the killing of Hamas political leader Ismail Haniyeh in Tehran late last month.

The Islamic republic and its allies have blamed Israel for Haniyeh's killing on 31 July during a visit to the Iranian capital for the swearing-in of President Masoud Pezeshkian. Israel has not commented.

Iran has vowed to avenge the death, which came hours after an Israeli strike in Beirut killed a senior commander of Hezbollah, the powerful Iran-backed militant group in Lebanon.

Western diplomats have scrambled to prevent a major conflagration in the Middle East, where tensions are already high due to the Israel-Hamas war in Gaza.

In a statement on Monday, the United States and its European allies urged Iran to de-escalate.

The White House warned that a "significant set of attacks" by Iran and its allies was possible as soon as this week, saying Israel shared the same assessment.

The United States has deployed an aircraft carrier strike group and a guided missile submarine to the region in support of Israel.

Iran's foreign ministry spokesman Nasser Kanani criticized the Western call for restraint.

"The declaration by France, Germany and Britain, which raised no objection to the international crimes of the Zionist regime, brazenly asks Iran to take no deterrent action against a regime which has violated its sovereignty and territorial integrity," he said in a statement.

The United States and its European allies also called for a ceasefire between Israel and Hamas in Gaza, with difficult talks set for Thursday on halting the conflict.

International mediators have invited Israel and Hamas to resume negotiations this week on a ceasefire and hostage release deal, an invitation Israel has accepted.

Far-right parties in Prime Minister Benjamin Netanyahu's ruling coalition strongly oppose any ceasefire in Gaza, a point rammed home by firebrand National Security Minister Itamar Ben Gvir on a visit to Jerusalem's flashpoint Al-Aqsa Mosque compound that was swiftly condemned by its custodian Jordan.