"Despite federal laws that say u.s. trade embargoes may not restrict the free flow of information, the Treasury Department's Office of Foreign Assets Control (OFAC) regulated the import of books from Iran and other embargoed countries. Though the ban did not purport outright to obstruct the flow of information between nations, it effectively did so by prohibiting the publication of "materials not fully created and in existence."
You can publish a book, in other words, but it would be illegal for a literary agent, publisher, or editor assist the author, and probably illegal to even advertise the book. Penalties were stiff fines and jail time.
"In Iran, the Islamic system censors books, cats up Internet firewalls, and bans satellite television in an effort to prevent Iranians from accessing information from the outside world. It seemed incomprehensible to me that the u.s. government, the self-proclaimed protector of a free way of life, would seek to regulate what Americans could or could not read, a practice that is called censorship when enacted by authoritarian regimes. What was the difference between the censorship in Iran and this censorship in the united states?" (Iran Awakening, p 211)