Former Barca winger and now PSG star Ousmane Dembele won the vote overwhelmingly from second-place Yamal.
But Xavi, who gave the winger his debut at 16 years of age, said at a World Cup presentation in New York: "I am very proud of what Lamine is doing and to have given him the opportunity to start.
"I saw that he was ready despite his fifteen years. He seemed very sure of himself, with a lot of qualities.
"For me, he is one of the chosen ones, and he can mark an era in world football. He has no complexes, no fears.
"This time, the collective titles weighed more. For me, of course he deserved it. Vitinha too, Salah, Pedri, Raphinha… many deserved it, but in the end, it is the trophies that make the difference.
"Lamine will win it, I am convinced of it, but it will be when his team wins the Champions League or a World Cup."