Yet reports in recent months suggest that conservative media, including blogs and news websites, have also been increasingly targeted by censors. The censorship has increased in the run-up to the June 14 presidential election.
The actions have led to a rare protest by more than 100 media activists -- said to be involved in managing semiofficial news agencies and conservative websites -- who have criticized the increased pressure against online media.
The activists write in their statement, issued over the weekend by the semiofficial Mehr news agency, that one of the bodies in charge of media work has in recent months taken "tough" and "unexpected" measures against the country's "known and official media."
The statement adds that "multiple centers of decision making" in cyberspace is one of the main problems media face in their online activities.
It says that for official media, being contacted by an unrelated body and ordered to remove some content or face filtering has become a "trend" in the past year.
The signatories of the statement warn that the actions damage Iranian society's mental health and commitment to the principle of news dissemination.
Mehr says the activists are protesting against the actions of the so-called filtering committee, which is in charge of identifying online content that should be blocked according to its criteria.
The committee has in recent weeks ordered the blocking of a number of websites, including several websites associated with Esfandiar Rahim Mashaei, the top aide to President Mahmud Ahmadinejad whose application to run in the presidential race was rejected.
The committee is only one of several entities involved in Iran's broader efforts to control online activities and enforce censorship. The main one is the Supreme Council of Cyberspace, which is an oversight body in charge of policy making.
For more on the different bodies involved in Iran's Internet censorship, check out this graph by the Iran media program at the University of Pennsylvania's Annenberg School for Communication.