The former Manchester United shot-stopper joined the Ligue 1 strugglers over the weekend on a six-month deal, although there is an additional one-year option.
Barthez instantly played down talk he could return to the international fold, stating he was simply looking to get fit and concentrate on his club commitments.
Nantes are currently struggling at the wrong end of the Ligue 1 ladder and Barthez does not want to be seen as the man to save the club from the drop.
"I've not even thought about the French team," he stated. "To wear Les Bleus' shirt you have to be at 400 per cent or even 500 per cent for your club.
"If the blue shirt should come, it will come. I remain a candidate, yes. I will resume playing when my coach decides.
"In about three weeks I will be at 90 per cent and after two or three matches I could be at my best again. But I am not the hero to come and save Nantes, I hate that.
"The idea is to be a player again, be happy and enjoy my football. Passion for football will always remain inside of me. It is in my blood, I was born with that."
Meanwhile, the club have been quick to play down talk former France international Laurent Blanc could replace George Eo at the helm in the New Year.
"Eo will remain at the helm," stated chairman Rudy Roussillon. "I appreciate his work and the whole club is backing him.
"Everything that has been said last week about his possible departure or replacement is absolutely fake. There has been no contact with anyone."
Finally, the club are being linked with a move for Monaco striker Sebastien Grax when the transfer window reopens in January.
Nantes, who are the league's lowest scorers with just 12 league goals to their name this term, and have made bolstering their strike-force a top priority.