The Teheran prosecutor filed a lawsuit against two Web sites and their license holders for insulting President Mahmoud Ahmadienjad.
A report Tuesday on Iranian state TV says the prosecutor's suit targets the conservative Jahannews and Alef news Web sites.
Alef belongs to lawmaker Ahmad Tavakkoli, who has often criticized Ahmadinejad.
Jahannews asserted in October that Ahmadinejad helped foment Iran's postelection unrest with his rhetoric against opponents.
The lawsuit appears to be part of a government crackdown on dissent.
Iran also has a long history of closure of media. Authorities have banned hundreds of newspapers, magazines and Web sites, and arrested dozens of journalists and bloggers since 2000.