"Irrational regimes" like Iran cannot be allowed to have nuclear arms, Israeli Prime Minister Benjamin Netanyahu said on U.S. television, the Reuters news agency reported.

Netanyahu, who met President Barack Obama last week during a visit to Washington and New York, told "Fox News Sunday" that Iran was "just moving on with its efforts" to develop nuclear weapons -- a prospect he called "very, very dangerous."

Asked whether a nuclear Iran could be contained, he said: "No, I don't. I think that's a mistake, and I think people fall into a misconception."

"I don't think you can rely on Iran," Netanyahu said in a taped interview. "And we should not allow irrational regimes like Iran to have nuclear weapons. It's the ultimate terrorist threat today."

Netanyahu declined to say whether he had any deadline for allowing diplomacy with Iran to run its course.

"We always reserve the right to defend ourselves," he said, reiterating a core policy of Israel, which does not confirm or deny widely held beliefs that it has the only nuclear arsenal in the Middle East.

Iran says its nuclear program is for peaceful purposes only. But the United States and its allies fear Tehran is pursuing an atomic weapons program and have pushed a series of United Nations and unilateral sanctions against Iran.

"There's only been one time that Iran actually stopped the program and that was when it feared U.S. military action," Netanyahu said.