Israeli Prime Minister Benjamin Netanyahu says he wants to talk soon to the new US president to "counter the threat" from Iran's government, which he accused of threatening its citizens' freedom.

"I plan to speak soon with President [Donald] Trump about how to counter the threat of Iranian regime which calls for Israel's destruction," Netanyahu said in a video message posted on his Facebook page on Saturday.

In the video, Netanyahu also addressed the people of Iran in English, with Persian subtitles.

"We are your friend, not your enemy," he said.

"The regime is cruel - the people are not; the regime is aggressive - the people are warm ... You have a proud history. You have a rich culture. Tragically, you are shackled by a theocratic tyranny," he said.

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Before his inauguration on Friday, Trump had repeatedly denounced a nuclear deal between Iran and six world powers, including the United States, which Israel has also staunchly criticised.

On January 16, Trump said in an interview with the Times of London and Bild newspaper of Germany: "I'm not happy with the Iran deal, I think it's one of the worst deals ever made. I think it's one of the dumbest deals I've ever seen, one of the dumbest."

But he declined to say whether he intended to "renegotiate" the deal, as he asserted regularly during the presidential campaign.

Netanyahu has been an ardent opponent of the 2015 pact signed by Iran, the US, China, Russia, Britain, France and Germany.

The deal placed curbs on Tehran's nuclear programme in exchange for the lifting of international sanctions.

In December, Netanyahu said there were many ways of "undoing" the Iran nuclear deal and that he would discuss that with Trump. "I have about five things in mind," he said.

But before he left office, former US President Barack Obama warned against rowing back the pact, emphasising its "significant and concrete results".