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 Iran's Supreme National Security Council, Ali Larijani, had met Russian President Vladimir Putin, where they discussed Middle Eastern and international issues among other matters.

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.

Asked on Friday whether he had given Tehran a deadline by which to strike a deal, Trump said that only they know for sure. He told reporters: Hopefully we'll make a deal. If we do make a deal, that's good. If we don't make a deal, we'll see what happens.

On Thursday, he indicated a large Armada was on its way to the region and declined to give a timeline for its withdrawal: We'll see how it all works out. They have to float someplace, so they might as well float near Iran.

Iran's Foreign Minister Abbas Araghchi had stated earlier that the country's missile defence systems would never be on the negotiating table, and repeated the government's position that its nuclear programme was peaceful.

At a press conference with his Turkish counterpart after talks in Istanbul aimed at averting US action, he mentioned that preparations were needed for fair and just negotiations.

Trump's warning regarding a nuclear deal came after he had promised Washington would intervene to help those affected by a brutal crackdown on protests in Iran earlier this month, stating help was on the way, and noting the cessation of demonstrator executions.

The US-based Human Rights Activists News Agency (HRANA) reported over 6,300 killed, with more than 5,900 of those being protesters since unrest began at the end of December, and investigated further potentially 17,000 reported deaths amid an internet shutdown following nearly three weeks of turmoil, while the Norway-based Iran Human Rights (IHR) warned that the final toll could exceed 25,000.