Iran warns US against 'strategic mistake' after Trump threat

Iran warned the US on Tuesday against making a "strategic mistake" after President Donald Trump threatened Tehran over reports it planned to avenge the killing of top general Qasem Soleimani.

"We hope that they do not make a new strategic mistake and certainly in the case of any strategic mistake, they will witness Iran's decisive response," Iranian government spokesman Ali Rabiei told a televised news conference.

Trump vowed on Monday that any attack by Iran would be met with a response "1,000 times greater in magnitude," after reports that Iran planned to avenge the killing of top general Qasem Soleimani.

A US media report, quoting unnamed officials, said that an alleged Iranian plot to assassinate the US ambassador to South Africa was planned ahead of the US presidential election in November.

"According to press reports, Iran may be planning an assassination, or other attack, against the United States in retaliation for the killing of terrorist leader Soleimani," Trump tweeted.

"Any attack by Iran, in any form, against the United States will be met with an attack on Iran that will be 1,000 times greater in magnitude!"

Rabiei expressed regret that "the president of a country who has claims to global management and order would make hasty, agenda-fuelled and dubious remarks on such a weak basis."

He warned that reacting to such reports would "achieve nothing but disruption to the region and to world calm" and advised Trump to "refrain from fresh adventurism... for the sake of winning a new term as president."

On Monday, Iran's foreign ministry denied the report of an assassination plot as "baseless" and part of "repetitive and rotten methods to create an anti-Iranian atmosphere".

Relations between Washington and Tehran have been tense ever since the Islamic revolution of 1979.

They have deteriorated sharply since Trump unilaterally pulled out of a landmark international nuclear deal with Iran in May 2018 and reimposed crippling sanctions.

Secretary of State Mike Pompeo on Monday declined to comment directly on the reported threat to Lana Marks, the US ambassador to South Africa, who is a close ally of Trump.

But Pompeo told Fox News that "the Islamic Republic of Iran has engaged in assassination efforts all across the world. They have assassinated people in Europe and in other parts of the world. We take these... allegations seriously.

"We make very clear to the Islamic Republic of Iran that this kind of activity -- attacking any American any place at any time, whether it's an American diplomat, an ambassador or one of our service members -- is completely unacceptable."

The Iranian navy last week said it drove off US aircraft that flew close to an area where naval exercises were underway near the Strait of Hormuz.

The military said three US aircraft were detected by air defences.

One of them was a US RQ-4 drone, the same model as one shot down by Iran in June last year after allegedly violating Iranian airspace -- a claim the US has denied.