The late-December clashes between reformists and Iranian security forces were the bloodiest since the protests following June's highly controversial presidential election – one opposition supporters say was rigged in favor of incumbent Mahmoud Ahmadinedad.
Eight people, including opposition leader Mir Hossein Mousavi's nephew, died in the violence Dec. 27. More than 40 pro-reform figures have been arrested.
According to the report, Intelligence Minister Heidar Moslehi told state television that "several foreigners … were leading a psychological war against the system" and had been arrested.
Moslehi didn't indicate the nationalities of the foreigners, but said their cases would be handed over to the judiciary by Wednesday.
The battle between the two sides has become increasingly bitter. Pro-government hardliners have called for the execution of Mousavi and other opposition leaders. And an unknown group posted a message online indicating suicide squads would assassinate reformist leaders if the government failed to prosecute them.
Mousavi, in response to the threats, said in a statement he was "not afraid to be one of the martyrs people have offered in the struggle for their just demands."