There has been claims the former Manchester United forward was axed over discipline and commitment problems.
But De Zerbi insisted on Friday: "We need to clarify the Mason Greenwood case a little, because you journalists are always in a position to change things a little, to create some scoops, because you have to do what all journalists do a little bit which is to make a little bit of chaos.
"Greenwood is a very good person whom I love, as I love his father.
"He's had a bit of a tough time lately because he had a daughter who was born, and I don't think he's used to playing such an intense season and being a main player. I think he paid for it physically.
"That is to say that he didn't push himself and wasn't 100 percent as I wanted in training, in terms of what I expect from a player like him.
"His physical condition has declined a little, but my project in Marseille is not only to qualify for the Champions League, it is also to create something like what Luis Enrique has created (at PSG). He has created a team, a group of strong players, but with a soul."