US President Donald Trump threatened further strikes against Iran on Monday after the first exchange of direct attacks in a month, raising tensions in a conflict that had recently shifted into an economic standoff.

Iran launched missiles overnight at two US air bases in Jordan in response to a US attack on Iran's Larak Island, where Washington said it had struck Iranian launchers firing mines into the Strait of Hormuz.

"We're going to hit them hard," a Fox News reporter quoted Trump as later telling the channel. "There will be a response."

Trump said US forces allowed one Iranian missile to pass through air defenses overnight after determining it would not hit anything, while the other incoming missiles were intercepted.

Separately, Trump told reporters in the Oval Office that the renewed strikes did not signal a return to full-scale war, describing Iran as a "failed nation" whose economy and military had been severely degraded. "That doesn't mean we won't smack them. We'll see what happens."

A senior Iranian source told Reuters the overnight exchanges of fire, the first since late July, were a "limited and contained confrontation" but said Tehran would deliver a harsh response if attacked again.

UN Secretary-General Antonio Guterres called for maximum restraint following the resumption of hostilities over the weekend between the US and Iran and encouraged a return to diplomatic talks that would lead to a settlement to help restore stability in the region, his spokesperson Stephane Dujarric said Monday.

Piling on economic pressure

The renewed military exchanges came as Washington has stepped up economic pressure on Tehran and its business partners, imposing "secondary sanctions" on third countries that buy Iranian oil.

US Treasury Secretary Scott Bessent said that Iran was "lashing out" now because the new sanctions were taking a toll on its economy.

Bessent told Reuters on Sunday that new secondary sanctions were likely to be unveiled weekly in the effort to pressure Iran, with an initial focus on banks.

The latest escalation has also heightened concerns over shipping through the Strait of Hormuz, a vital global energy transit route.

Iranian state TV quoted Iran's Islamic Revolutionary Guard Corps as saying a supertanker had caught fire and been brought to a halt after being struck by two naval mines in the south of the Strait of Hormuz. The US military later denied the claim.

Over the past month, Washington has hoped a blockade of Iranian ports will inflict enough economic damage to force Iran to comply with US demands. Tehran, meanwhile, has maintained that the Strait of Hormuz is shut and will reopen only under its supervision.

The number of visible commodity vessels transiting the strait dropped to five per day over the weekend, data from commodities firm Kpler showed.

A tanker has reported being struck by three projectiles while sailing out of the strait, 17 nautical miles east of Oman's Khasab, the United Kingdom Maritime Trade Operations agency (UKMTO) said on Tuesday. No casualties or environmental impact have been reported, UKMTO said.

(With input from agencies)