Neymar is demanding Barca pay bonuses to the tune of €30m he believes he is owed.
Mestre told El Mundo Deportivo: "Morally, he does not have the right to ask anything for something he has not done.
"We thought that if we offered him conditions, it was for him to fulfill them. If he does not fulfill them, you do not have to compensate. The judge will decide what we must do.
"In this sense, I am disappointed by Neymar. But also by his attitude last summer."