Police are also speaking to a sixth person, a woman, as a witness.
The five men allegedly posted several contributions to online forums in which they defended jihad and called for believers to participate in the holy war against non-Muslims.
The postings amounted to "jihadist indoctrination", according to one source connected to the inquiry.
The arrests form part of an investigation first opened in 2008 by the Paris anti-terrorism unit.
All five men have been remanded in custody and their homes and computers searched for evidence.
Under France's anti-terrorism laws, suspects may be detained for four days without charge, at which point they must either be released or sent before a judge.