The French international has been persistently linked with a move to the Premier League, with Lille rejecting two bids from Newcastle.
Lille boss Garcia thinks that Debuchy needs to deal with situation and start to focus on playing in Ligue 1 this season.
He told Nord Eclair: "He doesn't really have the choice. The club has made a decision and he has to deal with it.
"He also knows he has to be good in the game for his future in the French team. I have no worries about him."
Toon manager Alan Pardew has not given up hope of signing the full-back but time is running out for the two clubs to agree a transfer fee.