Iran has written to the UN nuclear watchdog to complain about Israel's threats against its nuclear sites in a possible retaliatory strike, foreign ministry spokesperson Esmail Baghaei said on Monday.

“Any acts of aggression towards nuclear sites are condemned under international law,” Baghaei said during his weekly news conference.

He added that Tehran had officially communicated its position to the International Atomic Energy Agency (IAEA), saying, "we have sent a letter about it to… the UN nuclear watchdog."

Israel has vowed to attack Iran in retaliation for a volley of Iranian missiles launched on October 1, leading to widespread speculation that Iran's nuclear sites could be among Israel's targets.

On October 1, Iran fired more than 180 missiles at Israel, a move described as retaliation for the killings of Hamas leader Ismail Haniyeh in Tehran and Hezbollah Secretary General Hassan Nasrallah in Lebanon. It was the second Iranian attack on Israel this year. Israel responded to the first missile volley in April with an air strike on an air defense site in central Iran.

After the attack, Prime Minister Benjamin Netanyahu warned that Tehran had made a “big mistake tonight” and vowed that “it will pay for it.” Later, the Biden administration revealed that it told Israel not to attack Iran's nuclear sites.

Last week, Netanyahu's office said Israel would listen to key ally the United States regarding a response to Iran's missile attack but would decide its actions according to its own national interest.

His statement was attached to a Washington Post article which said Netanyahu had told President Joe Biden's administration that Israel would strike Iranian military targets, not nuclear or oil sites.

Baghaei, responding to a question about the possibility of Iran changing its official nuclear doctrine, said "weapons of mass destruction have no place in our policy". Tehran would decide on how and when to respond to any Israeli attack.

Israel, which has long accused Tehran of plans to develop nuclear weapons, regards Iran's nuclear activities as a threat. Tehran denies these accusations, insisting that its program is entirely peaceful.

Additionally, Israel’s former premier Naftali Bennett called for the country’s leaders to launch an attack on Iran’s nuclear facilities as the Jewish state weighs its response to the barrage of 181 ballistic missiles.

Bennet slammed Biden who had called for a “proportionate” response, saying, "President Biden has said that Israel can retaliate against Iran, but must keep the response 'proportionate'. The president also urged Israel not to attack Iran’s nuclear program."

Moreover, prominent Israeli opposition lawmaker and former defense minister Avigdor Liberman also called on the government to use “all the tools” at its disposal to confront the threat of Iran’s nuclear program, tacitly suggesting that Israel should use a nuclear weapon against the Islamic Republic.

“In order to stop the Iranian nuclear program, which is already at weaponization stages, we must use all the tools at our disposal... It must be clear that, at this stage, it is impossible to prevent Iran from obtaining nuclear weapons via conventional means.”

Separately, Baghaei said Iranian Foreign Minister Abbas Araghchi would travel to Bahrain and Kuwait on Monday as part of Iran's efforts to curb regional tensions.

Since early October, Araghchi visited Turkey, Jordan, Egypt, Syria, Saudi Arabia, Qatar, Iraq, and Oman, with the primary goal of mitigating an Israeli strike.

Iran also remains defiant on the issue of three Persian Gulf islands disputed by UAE, with Baghaei reaffirming that Tehran “has no doubt about its territorial integrity and sovereignty over the three islands” in the face of claims from Persian Gulf states and the European Union, which accuse Iran of occupying the islands.

Tensions with Europe were also highlighted during Baghaei’s briefing, as he accused European governments of escalating hostilities by failing to engage constructively with Tehran.

European nations have recently imposed sanctions on Iran, citing its nuclear activities and human rights abuses.

When asked about reports of Israeli military preparations, Baghaei downplayed media speculation but stressed Iran’s readiness to defend itself.

“Our focus will be on responding to any kind of malicious act,” he stated, without specifying potential countermeasures.

Iran's rhetoric and diplomatic outreach suggest that the Islamic Republic is bracing for a critical confrontation in its longstanding conflict with Israel.