Messi is out of contract at the end of the season and the superstar Barca captain has been heavily linked with Ligue 1 champion PSG and Premier League leader Manchester City.
Barca – led by new president Joan Laporta – remains hopeful of re-signing the record six-time Ballon d'Or winner, who has spent his entire senior career at Camp Nou.
Di Maria has played alongside Messi at international level for Argentina and the PSG star admitted he would love to join forces with his countryman at club level.
"From my whole career, from everything I've seen, I think Leo is from another planet," Di Maria said. "To have him as a team-mate would be wonderful.
"But he is a Barcelona player, he has a contract. After that, we'll see.
"I talk a lot with him and I always tell him that the important thing is his happiness and that of his family. It's hard to say anything else."