Iran yesterday warned the US 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!"

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".