US President Donald Trump has warned Iran that “time is running out” to strike a deal on its nuclear weapons program.

His comments follow the build-up of US military forces in the Gulf, which Trump said was a “massive armada” floating towards Iran.

Trump said the next US attack on the Middle Eastern nation would be “far worse” if Iran refused to reach an agreement.

“Hopefully Iran will quickly ‘Come to the Table’ and negotiate a fair and equitable deal — NO ‌NUCLEAR WEAPONS — ​one that is good for all parties,” Trump posted to Truth Social.

“Time is running out, it is truly of the essence!”

Trump noted ​that his last warning to Iran was ‍followed by a military strike.

“The next attack will be far worse! Don’t make ​that happen ​again,” he wrote. ​

Separately, during a speech in Iowa, Trump said “another” US military fleet is on its way to Iran”.

“By the way, there’s another beautiful armada floating beautifully toward Iran right now. So, we’ll see,” Trump said.

It was not immediately clear whether Trump was referring to the aircraft carrier USS Abraham Lincoln and the accompanying warships that arrived in the Middle East on Monday (local time), or to other US military forces.

Iran hit back with its own strong statement in capital letters, vowing that it would “respond like never before” if pushed.

“Last time the US blundered into wars ​in Afghanistan and Iraq, it squandered over $US7 trillion ($10 trillion) and lost ‌more than 7000 American lives,” Iran’s UN mission said in an X post quoting Trump’s statement.

“Iran stands ready for dialogue based on mutual respect and interests – BUT ​IF PUSHED, IT WILL DEFEND ITSELF AND RESPOND LIKE NEVER BEFORE!”

Iranian Foreign Minister Abbas Araqchi said ‍he had had no contact with US special envoy Steve Witkoff in recent days nor requested negotiations, state media reported on Wednesday.

Iran’s mission to the UN said Tehran also “stands ready for dialogue based on mutual respect and interests”.

Iran has been in the midst of a bloody crackdown on nationwide protests, which human rights activist says has killed more than 6100 people.

Trump has been encouraging the protests and threatening US military intervention.

Meanwhile, the responsible regional command of the US military, CENTCOM, announced a multiday air force exercise in the Middle East.

On Monday (local time), CENTCOM said a fleet of warships, including the USS Abraham Lincoln, had arrived in its area of responsibility, which includes Iran.

Trump recently refused to rule out military intervention by the US in Iran following a violent crackdown on protests which, according to rights groups and witnesses, resulted in thousands of deaths.

With regard to the leadership in Tehran, Trump said in Iowa: “I hope they make a deal.”

He had previously told the US news portal Axios that Iran was interested in a diplomatic solution to the tensions with the US. The situation with Iran is “in flux” because the US has sent a large fleet to the region, Trump told Axios in an interview.

-with AAP