Duff called time on his 100-cap career in the Republic's last game of Euro 2012 and vowed never to return to the international arena. But Tardelli plans to speak to the winger once the Republic's next two fixtures against Kazakhstan and Oman are out of the way in the hope that he can change the player's mind.
"I know he has said he has retired, but I hope he will be back for the Germany game. It is possible," Tardelli said. "I don't know if he will or not, but I always see him during Fulham's matches and I think it is possible, why not? He is a very good player. He said he has stopped but I hope he will come back."
The Republic will look to put their Euro 2012 disappointment behind them this Friday by starting their World Cup qualification campaign with a win in Kazakhstan.
The three defeats in Poland have led to questions about the future of head coach Giovanni Trapattoni, who was dealt a blow last week when Darron Gibson refused a call-up because he was disappointed with his failure to play during the European Championship.
Tardelli, who has worked under Trapattoni during his four years in charge, has hit out at his compatriot's critics and claims that the 73-year-old is more determined than ever to lead the Republic to success.
"Giovanni wants to work always every day. He is full of enthusiasm, just like he was the first time I met him," Tardelli added.
"I don't understand why Giovanni is (being criticised).. because he achieved good results."