US President Donald Trump has urged Iran to come to the table and make a deal on nuclear weapons or the next US attack would be far worse, but Tehran said if that happened it would strike back.
"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. Time is running out, it is truly of the essence!" Trump wrote in a social media post.
The Republican US president, who pulled out of world powers' 2015 nuclear deal with Tehran during his first White House term, noted his last warning to Iran was followed by a military strike in June.
"The next attack will be far worse! Don’t make that happen again," Trump wrote. He also repeated a US "armada" was heading toward the Islamic Republic.
Iranian Foreign Minister Abbas Araqchi warned on social media platform X that Iran's armed forces "are prepared - with their fingers on the trigger - to immediately and powerfully respond to ANY aggression".
"At the same time," Araqchi added, "Iran has always welcomed a mutually beneficial, fair and equitable NUCLEAR DEAL - on equal footing, and free from coercion, threats, and intimidation - which ensures Iran's rights to PEACEFUL nuclear technology, and guarantees NO NUCLEAR WEAPONS."
Araqchi said earlier he had not been in contact with US special envoy Steve Witkoff in recent days or requested negotiations, state media reported on Wednesday.
Iran's mission to the United Nations also responded to Trump's post.
"Last time the US blundered into wars in Afghanistan and Iraq, it squandered over $US7 trillion ($A10 trillion) and lost more than 7000 American lives," it 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!"
Trump said a US naval force headed by the aircraft carrier USS Abraham Lincoln was approaching Iran. Two US officials told Reuters on Monday that the Lincoln and supporting warships had arrived in the Middle East.
The warships started moving from the Asia-Pacific region last week as US-Iranian tensions soared following a bloody crackdown on protests across Iran by its clerical authorities in recent weeks.
Trump has repeatedly threatened to intervene if Iran continued to kill protesters, but the countrywide demonstrations over economic privations and political repression have since abated.
He has said the United States would act if Tehran resumed its nuclear program after the June air strikes by Israeli and US forces on key nuclear installations.
A spokesperson for Iran's Islamic Revolutionary Guard Corps said Iran has devised operational plans for all scenarios.
Earlier on Wednesday, US Secretary of State Marco Rubio told a congressional committee the Iranian government is probably weaker than it has ever been and its economy is in collapse. He predicted protests will spark up again.
