The 26-year-old Austria international has attracted interest from Panathinaikos, who reportedly tabled a €1.5million bid for the player on Thursday.
Gordon Strachan: "A Greek club has offered us money for him.
"But it's not something we're interested in.
"If we tried to get the same type of player to replace him, or maybe one who is not even as good as him, it would cost us more than five times what the other team (Panathinaikos) are offering. So it's not worth it.
"Poggy is fine about it. He understands our position and that it won't happen.
"He's one of our big men, one of the really big figures at this club, and his leadership is invaluable to us."