Now retired, Mascherano explained that it's not his place to say what Messi should do after his contract expires, but added that he will back whatever the No.10 decides.
"I think he's doing good, apart from the fact that Barcelona aren't having their best moment in a sporting sense," Mascherano said at a LaLiga event.
"His body language and play in this season hasn't changed with respect to the previous 15 years.
"At all big clubs, players eventually leave at some point. It's the clubs that stay.
"With Messi, I would never give him any advice because he is the one who has to decide. But, as a friend, I will support whatever decision he takes."