Tewari was taking political questions at a press conference in Panaji ahead of the inauguration ceremony of the International Film Festival of India (IFFI).
Responding to a question as to whether Modi should resign following the revelations of the controversial tapes, Tewari said: "Resignations should be sought from those who have morals."
"If he had any shame, he would have resigned after the 2002 pogrom in Gujarat. This is a shame," Tewari further said, without naming Modi directly.
The image of Narendra Modi and his aide Amit Shah is under cloud after the tapes released by the media last week revealed that a woman allegedly had been put under surveillance by the state government.
The tapes also revealed that the state anti-terror police was allegedly keeping tabs on her, purportedly on the request of her father who feared for his daughter's safety.
"It is a travesty. Putting people under unauthorised surveillance is a criminal offence, which is punishable under our constitution," Tewari said.