US President Donald Trump said on Thursday he hoped to avoid military action against Iran, which has threatened to strike American bases and aircraft carriers in response to any attack.

Trump said he is speaking with Iran and left open the possibility of avoiding a military operation after earlier warning that time was “running out” for Tehran as the United States sends a large naval fleet to the region.

When asked if he would have talks with Iran, Trump told reporters: “I have had and I am planning on it.”

“We have a group headed out to a place called Iran, and hopefully we won’t have to use it,” the US president added, while speaking to media at the premiere of a documentary about his wife Melania.

As Brussels and Washington dialled up their rhetoric and Iran issued stark threats this week, UN chief Antonio Guterres has called for nuclear negotiations to “avoid a crisis that could have devastating consequences in the region”.

An Iranian military spokesman warned Tehran’s response to any US action would not be limited — as it was in June last year when American planes and missiles briefly joined Israel’s short air war against Iran — but would be a decisive response “delivered instantly”.

Brigadier General Mohammad Akraminia told state television US aircraft carriers have “serious vulnerabilities” and that numerous American bases in the Gulf region are “within the range of our medium-range missiles”.

“If such a miscalculation is made by the Americans, it will certainly not unfold the way Trump imagines — carrying out a quick operation and then, two hours later, tweeting that the operation is over,” he said.

An official in the Gulf, where states host US military sites, told AFP that fears of a US strike on Iran are “very clear”.

“It would bring the region into chaos, it would hurt the economy not just in the region but in the US and cause oil and gas prices to skyrocket,” the official added.

‘Protests crushed in blood’

Qatar’s leader Sheikh Tamim bin Hamad Al Thani and Iran’s President Masoud Pezeshkian held a call to discuss “efforts being made to de-escalate tensions and establish stability,” the Qatar News Agency (QNA) reported.

The European Union, meanwhile, piled on the pressure by designating the Islamic Revolutionary Guard Corps (IRGC) a “terrorist organisation” over a deadly crackdown on recent mass protests.

“‘Terrorist’ is indeed how you call a regime that crushes its own people’s protests in blood,” said EU chief Ursula von der Leyen, welcoming the “overdue” decision.

Though largely symbolic, the EU decision has already drawn a warning from Tehran.

Iran’s military slammed “the illogical, irresponsible and spite-driven action of the European Union”, alleging the bloc was acting out of “obedience” to Tehran’s arch-foes the United States and Israel.

Iranian officials have blamed the recent protest wave on the two countries, claiming their agents spurred “riots” and a “terrorist operation” that hijacked peaceful rallies sparked over economic grievances.

In Tehran on Thursday, citizens expressed grim resignation.

“I think the war is inevitable and a change must happen. It can be for worse, or better. I am not sure,” said a 29-year-old waitress, speaking on condition of anonymity for fear of reprisals.

“I am not in favour of war. I just want something to happen that would result in something better.”

Another 29-year-old woman, an unemployed resident of an upscale neighbourhood in northern Tehran, told AFP: “I believe that life has highs and lows and we are now at the lowest point.”

Trump had threatened military action if protesters were killed in the anti-government demonstrations that erupted in late December and peaked on January 8 and 9.

But his more recent statements have turned to Iran’s nuclear programme, which the West believes is aimed at making an atomic bomb.

On Wednesday, he said “time is running out” for Tehran to make a deal, warning the US naval strike group that arrived in Middle East waters on Monday was “ready, willing and able” to hit Iran.

Iranian authorities acknowledge that thousands were killed during the protests, giving a toll of more than 3,000 deaths, but say the majority were members of the security forces or bystanders killed by “rioters”.

Billboards and banners have gone up in the capital Tehran to bolster the authorities’ messages. One massive poster appears to show an American aircraft carrier being destroyed.