On-loan from Real Madrid, Endrick has made an impressive impact on Ligue 1 since his January arrival.
But Giresse, who twice won the Ligue 1 championship and also the Euros with France, was critical of Endrick in OL's defeat to Marseille.
He said: "Then you have players like Endrick. He's presented as a player from another dimension. I'm still left wanting more. In these kinds of matches, he's supposed to make the difference.
"He had a magnificent opportunity when he attempted to control a very high ball. These types of players need to finish in important matches."
On OM's 3-2 win overall, Giresse told L'Equipe: "It was a match worthy of the occasion. I enjoyed it immensely. Both teams showed their total commitment. They were eager to create danger in the opposition's half when they had possession, to find scoring opportunities.
"The ball flowed smoothly from one side to the other. Marseille could have conceded a goal early on, but they stayed in the game until the final whistle. They never gave up and fought with all their might to win. Time flew by."