State radio said on Tuesday that the protest has been going on for several days.
The conditions, including isolation in cells and only one visit and one phone call each month, were introduced a decade ago as part of the state's crackdown on organised crime following the slaying in Sicily of Italy's top two anti-Mafia prosecutors.
The law imposing the conditions comes up for renewal every year. Now Premier Silvio Berlusconi's government is considering extending it for four years, and there are some lawmakers who want the tough treatment to continue permanently.
Proponents of the law says isolation makes it harder for mobsters to continue to run their illegal activities while behind bars, as was the case for decades.
The agitation began in Marina Picena, a prison in central Italy whose inmates include Salvatore Riina, the reputed "boss of bosses" who was arrested in 1993 in Palermo after years as a fugitive. The protest was going on in other top-security prisons.
Justice Ministry officials were not immediately available for comment about the protest. - Sapa-AP