Controversy has surounded Messi's participation in the event with Barcelona insisting that they wanted hm to play in at least one leg of their Champions League qualifiers next month.
"I have always said I want to play for the national team and I want to thank the club for the way they have been with me," he told reporters after the game in Florence.
Club captain Xavi Hernández admitted that the Blaugrana were powerless once FIFA had insisted that all clubs release their Under-23 players.
"We want Messi to be here and Argentina want him there. He is a decisive player and we cannot do anything. FIFA is that one that decides," he told the club's official website.
Gerard Piqué agreed with his skipper and stated that the ruling was unfair,but that he understood Argentina's desire to have the exciting forward in their side.
"The players have to stay out of things, but from our point of view we think its unfair that Messi cannot play with us, but for them it is also important to have him. We have to accept the decision," he added.