Former Real Sociedad coach Lasarte gave Griezmann his first team breakthrough at San Sebastian as a youngster.
The Uruguayan told Esports Cope: "Antoine is sad. But I don't think it's because he's not the best, because he's always been very clear about the fact that (Lionel) Messi is the best.
"He fulfilled his dream, which is to play with Messi.
"Antoine is very intelligent and I think if he is sad it is because things do not go as he wanted."