Barca have declared they will sell Dembele after he refused to sign a new contract this month. The Frenchman also won't be considered for selection.
The AFE said in a statement: "A club is obliged to pay a player the agreed wages and allow the provision of services under the same conditions as the rest of his teammates, without there being any type of discrimination or pressure for the athlete to waive their working rights," said the AFE on Thursday.
"The renewal of a contract requires the agreement of both parties. Said agreement must be issued freely without any external conditions that limit the player's freedom. A footballer does not have the right to be called up for every match, but they must be treated under the same conditions as their teammates.
"If [Barca's actions] can be understood as pressure to break his will -- and if public statements are also made acknowledging this type of pressure -- we would be looking at illegal conduct.
"The AFE considers that not reaching an agreement to renew a contract does not imply a labour breach, so it cannot have any consequences. Not picking a player for a period of time without any injury, illness or physical impediment, supposes a devaluation of his image that will negatively affect his future contracts."