President Donald Trump has said Iran wants to make a deal rather than face US military action, despite Tehran's insistence that its missile and defence systems will never be up for negotiation.

I can say this, they do want to make a deal, Trump told reporters at the White House on Friday when asked about a build-up of US military forces in the Gulf, without providing details.

He had warned Tehran on Wednesday that time was running out to negotiate a deal on its nuclear programme after a large US naval fleet had gathered near the country.

Iran's foreign minister said there were no talks planned with the US at present but that Tehran was open to negotiations based on mutual respect and trust.

Also on Friday, the Kremlin said the head of the Iran's Supreme National Security Council Ali Larijani had met Russian President Vladimir Putin. They discussed Middle Eastern and international issues among other matters, state news agency Ria-Novosoti reported.

Iran insists its nuclear programme is entirely peaceful and has repeatedly denied accusations by the US and its allies that it is seeking to develop nuclear weapons.

Trump's warning regarding a nuclear deal came after he had promised Washington would intervene to help those involved in a brutal crackdown on protests in the country earlier this month. He had said help was on the way, before saying he had been told the execution of demonstrators had stopped.

On Thursday, he said he had told Iran that it had to do two things to avoid military action: Number one, no nuclear. And number two, stop killing protesters.

The US-based Human Rights Activists News Agency (HRANA) said it had confirmed the killing of more than 6,300 people, including more than 5,900 protesters, since the unrest began at the end of December. Another group, the Norway-based Iran Human Rights (IHR), has warned the final toll could exceed 25,000.