Costa stood in for coach Sergio Conceicao after their 2-0 win against Monza for the Rossoneri's final game of the season.
"For Milan, the players and the fans, the objective must always be first place,” Costa told DAZN, standing in for the suspended Conceicao.
“We can start talking about the season tomorrow and why we finished in this position, but for tonight we should talk about this game.”
He also said: “This is a squad full of many players, they each have their own personalities, so it’s like a family, you need to get to know and understand each other.
“However, when it comes to tonight’s match, the start was sluggish, we did better after the restart with more intensity and are satisfied with the result. For the rest, we can talk tomorrow.”