Iran's Foreign Ministry spokesman Saeed Khatibzadeh has dismissed a report claiming that Iran was plotting to kill the US ambassador to South Africa, Lana Marks.
Citing two US officials, Politico reported on 13 September that Iran was planning to assassinate Ms Marks, a long-time friend of US President Donald Trump, in retaliation for the assassination of General Qasem Soleimani in January.
Questioning the source of the report, Mr Khatibzadeh said the article was "biased", the official IRNA news agency reported.
"We advise American officials to stop using old and tired methods to create an anti-Iranian atmosphere on the international stage," he added.
Soleimani was killed in a US drone strike on an airport in Baghdad in January, prompting Iran to strike an Iraqi air base housing US troops a week later.
It caused traumatic brain injuries among a number of American soldiers.