Foreign ministry spokesman, Hamid-Reza Assefi, said on Monday he hopes "the Zionist regime will not commit any adventurist act".
Assefi was responding to a journalist who referred to a report saying Israeli Prime Minister, Ariel Sharon, had recently raised the issue with US President, George Bush .
He said: "Israel has demonstrated that it is adventurist and does not respect any principles and, if it makes such a mistake, it will pay a very heavy price."
The Washington Post said last week that Sharon told Bush Iran was much closer to producing nuclear weapons than US intelligence believes.
"If it (Israel) makes such a mistake, it will pay a very heavy price"
Iranian foreign ministry
The comments are thought to have triggered concern that Israel is seriously considering a pre-emptive strike against Iran's Bushehr nuclear reactor.
International pressure has been mounting on Iran to allow more intrusive, short-notice inspections of nuclear sites in the country.
Iran denies any plans to build nuclear weapons and says its nuclear programme is purely for peaceful means.
But the question of whether to sign a protocol allowing the inspections, has ignited fierce domestic debate.
Tehran insists it should get access to Western nuclear technology to develop atomic energy in return for signing the protocol, something it says is stipulated in the Nuclear Non-Proliferation Treaty.