Katidis insists he did not know what the gesture meant
AEK Athens midfielder Giorgos Katidis, 20, made the gesture to celebrate his winning goal during a Saturday match.
The Greek football federation called it "a severe provocation" that insulted "all the victims of Nazi bestiality".
Katidis denied he gave a Nazi salute. "I am not a fascist and would not have done it if I had known what it meant," Katidis said on his Twitter account.
The player - a former captain of Greece's under-19 team - was fiercely criticised on social media for the salute after scoring the winner in AEK's 2-1 victory over Veria in the Olympic stadium on Saturday.
He insisted he was simply pointing at a team mate in the stands.
The club have asked him to explain himself at a board meeting next week.
But AEK's German coach Ewald Lienen has backed Katidis.
"He is a young kid who does not have any political ideas. He most likely saw such a salute on the internet or somewhere else and did it without knowing what it means," he said, according to Reuters news agency.
Greek PM promises Jewish leaders a law against Holocaust denial [Link]
What kind of truth needs laws to protect it?