Neymar was undoubtedly involved in the biggest transfer saga in the last window after announcing his desire to leave Paris Saint-Germain.
The move did not materialise and the Brazilian has remained with the Ligue 1 champions, but there are reports could still make a move for the player.
However, Messi felt it would have been tough bring Neymar back to the Camp Nou due to the way he left two years ago.
"It is difficult to bring him back," Messi told Metro 95.1 in Buenos Aires.
"Firstly, because it was difficult to see him leave, secondly because of how he left.
"There are people from the club and the members who do not want him to return.
"If it is for sports, Ney is one of the best in the world, but I understand all the other factors."