Martial was ignored by France coach Didier Deschamps for the World Cup this summer.
"I don't feel sorry for him because he had the opportunity," Gallas told Goal of his World Cup omission.
"He was in the squad many times before. I think he missed his chance go to the World Cup. He didn't perform at his best for the whole season. To go to the World Cup, you have to perform all season.
"You can't be up and down, that's what has made the difference. He is still young and maybe he will learn. He has great quality and it is a shame for him."