Iranian authorities have blocked reformist websites and detained several opposition supporters and activists, opposition website Saham News reported Thursday.
The arrests come days after Iran's two leading opposition figures called for a rally next Monday in support of the uprisings in North Africa and the Middle East.
Iranian authorities on Wednesday warned against any attempt by the opposition movement to hold the rally, according to the state-run Islamic Republic News Agency.
"We definitely see them as enemies of the revolution and spies, and we will confront them with force," Revolutionary Guard Cmdr. Hossein Hamedani told IRNA.