The 33-year-old quit international football following Ireland's Euro 2012 campaign after making his 100th appearance for his country.
"I know he has said he has retired, but I hope he will be back for the Germany game [next month]," said Tardelli. "It is possible.
"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."
Ireland will take on Germany in a 2014 World Cup qualifier next month after playing Kazakhstan this week.