In an interview with Marca, he also ruled out the possibility of leaving the Catalan side.
Neymar, 26, left Barca to join Paris Saint-Germain in a world record €222million deal in 2017.
Since leaving, he has regularly been linked with a return to the club, as well as a move to rivals Real Madrid.
And, while Messi said he believes a reunion for the pair in Spain is unlikely, he would be delighted should it happen.
“It would be difficult.We would love it if he came back for what he means as a player and in the dressing room.
“We are friends, we enjoyed nice moments, as well some which were not so nice, but we spent a lot of time together. It is undoubtedly difficult to imagine him leaving Paris. PSG won’t let Neymar go,” Messi said.