Iran has detained several local British embassy staff, sparking a new row with Britain on Sunday that underscored the hardline leadership's effort to blame post-election unrest on foreign powers, not popular anger, Reuters reported.
British Foreign Secretary David Miliband demanded the release of all the staff still held and said his European Union colleagues had agreed to a "strong, collective response" to any such "harassment and intimidation" against EU missions.
Supreme Leader Ayatollah Ali Khamenei denounced what he called "interfering statements" by Western officials following the disputed presidential election on June 12.
"If the (Iranian) nation and officials are unanimous and united, then the temptations of international ill-wishers and interfering and cruel politicians will no longer have an impact," state radio quoted him as saying.
The West is at odds with Iran over its nuclear programme, as well as its handling of the unrest.
The streets of Tehran have sunk back into a sullen calm since riot police and religious Basij militia crushed huge demonstrations in which at least 20 people were killed.
"Everybody is depressed, everybody is afraid," said one Mousavi voter in his 20s in northern Tehran.
On Sunday, one witness said riot police armed with batons and members of the Basij militia scuffled with some of more than 1,000 pro-reform Iranians who gathered outside Tehran's Qoba mosque to mark the anniversary of a 1981 bombing that killed dozens of senior officials.
The report could not be independently confirmed because of reporting restrictions on foreign press but an ally of election runner-up Mirhossein Mousavi played down the incident, saying only a small group had gathered amid a strong police presence.