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Iran's Foreign Minister, Hossein Amirabdollahian, said a "pre-emptive action" could be expected in the coming hours, state TV reported on Monday.
Mr Amirabdollahian said Israel will not be allowed to take any action in the Gaza Strip without facing consequences.
"Leaders of the Resistance will not allow the Zionist regime to take any action in Gaza," he told state TV.
"All options are open and we cannot be indifferent to the war crimes committed against the people of Gaza.
"The resistance front is capable of waging a long-term war with the enemy … in the coming hours. We can expect a pre-emptive action by the resistance front," he said, without elaborating.
Mr Amirabdollahian was referring to the so-called Axis of Resistance – a Tehran-backed network that encompasses militant groups in Palestine, Iraq, Hezbollah in Lebanon and the Syrian government
Mr Amirabdollahian said that "the resistance leaders" will not allow Israel "to do whatever it wants in Gaza".
"If we don't defend Gaza today, tomorrow we have to defend against these [phosphorus] bombs in the children's hospital of our own country," he said.
Last week, Iran's supreme leader Ayatollah Ali Khamenei said Tehran was not involved in the militant Hamas group's attack on Israel on October 7, but hailed what he called Israel's "irreparable" military and intelligence defeat.
Backing the Palestinian cause has been a pillar for Iran since the 1979 revolution and a way in which the Shiite-dominated country has fashioned itself as a leader of the Muslim world.
Tehran says it gives moral and financial support to Hamas, which controls the Gaza Strip.
Earlier on Monday, Iranian President Ebrahim Raisi said that while Tehran supported the Palestinian cause, the resistance front against Israel made its own independent decisions.
