Despite the youngster's struggles at Real Madrid, Scaloni says he has been included on merit.
He explained, "We are happy with Mastantuono, he is 18 years old. Without going any further, the boy who is playing for Boca now, Tomás Aranda, has come to train with us and is the same age as Franco.
"By this I mean that Franco is a boy, Aranda is a boy. We have to give them time."
Scaloni highlighted that "he is in a very demanding club (Real Madrid). The most demanding in the world. That makes everything magnified. It is enough for me that he understands his situation.
"With us Mastantuono will have all the support and above all he will understand that he has to go little by little, that his career is just beginning, that he has to keep moving forward."