Barcelona have been fined only €300 after being found guilty of tapping up Antoine Griezmann while he was an Atletico Madrid player.
Griezmann, the France international forward, joined Barcelona in July after they triggered his £108m release clause.
Atletico disputed the deal, claiming it was "obvious" Griezmann had agreed to the transfer before July 1 - when his release clause was £180m.
"Atlético de Madrid believes that the amount deposited is insufficient to meet [Griezmann's] buy-out clause, since it is obvious that the player committed to FC Barcelona before the aforementioned clause was reduced from 200 to 120 million euros," the club said in a statement.
"Atlético de Madrid believes that the termination of the contract occurred before the end of last season due to events, acts and demonstrations carried out by the player and that is why the club has already started the procedures it considers appropriate for the defense of its legitimate rights and interests."
Griezmann has scored three goals in his first seven games as a Barcelona player.
Barcelona are fifth in La Liga after losing two of their opening six matches.