The Greek is currently playing on-loan at Werder.
He told Bild: "On paper, it might be a fact I would have to stay on if Werder Bremen exercises the buy option.
"But we need to talk to each other first. Chances are 50-50. It will also depend on me.
"If a player is unhappy, he cannot stay on. And I am able to confirm I have received enquiries from other clubs."