“Such practices can threaten the peace between citizens living in the same country and lead to conflict”, Marzouki warned in a statement, reported to AFP.
He asked the president and members of the Constituent Assembly which in December approved the North African country’s new government to adopt legislation “that outlaws accusations of blasphemy”.
Violators of the new law should be prosecuted “to protect the coexistence, fraternity and solidarity among Tunisians,” he said.
“Nobody has the right to make such accusations against a fellow citizen because such behaviour risks leading to violence which is reprehensible in itself,” Marzouki added.
His comments came a day after Arabic-language newspaper Assabah published an interview with a radical Islamist who branded university professor Iqbal Gharbi as an infidel.
Salafists have also accused Tunisian journalists and other public figures of not following the teachings of the Koran, the Muslim holy book.
Tunisia’s moderate Islamist leaders, who took power following last year’s ouster of strongman Zine El Abidine Ben Ali, are under pressure from a radical Muslim fringe.
The ultra-conservative Salafists have in recent months demanded full-face veils for female university students, castigated a TV channel for an allegedly blasphemous film and beat up journalists at a protest.