"Takfiri groups hurt the message of Islam," Nasrallah said during a speech broadcast on a large screen in Beirut's southern Dahiyeh suburb, a Hezbollah stronghold.
"The danger posed by such groups to the region transcends politics," he asserted.
"The Islamic nation should resist the practices of terrorist and takfiri groups, which have nothing to do with Islam," Nasrallah said.
He went on to criticize the Bahraini authorities for detaining Shiite opposition leader Ali Salman earlier this week for "promoting violent political change."
"[Salman's] ongoing detention is a very serious matter," Nasrallah said.
He accused Bahrain's Sunni rulers of "executing a Zionist-like project" in the predominantly-Shiite Gulf statelet by "offering citizenship and jobs" to Sunni-Muslim foreigners.
"Authorities in Bahrain never held serious dialogue with the opposition," he said. "Instead, they dragged the desperate opposition to violent conflict."
Nasrallah also said there was "no substitute" for dialogue between Lebanon's rival political camps.
Violent conflict in Syria, now in its fourth year, has continued to fuel sectarian tension in Lebanon, where Hezbollah's ongoing military support for Syria's Alawite-dominated regime has drawn condemnation from Sunni groups.