The Catalan side made public their desire to bring Neymar back from PSG this summer, with the French champions keen to let the Brazil international go.
Messi had also made it clear he wanted his former teammate back, but the two clubs were unable to strike a deal for a player who cost a world-record €222 million when he left for Barca for PSG in 2017.
"We talk to Neymar often," Messi told Argentina's Radio Metro. "We still have a WhatsApp group with Luis [Suarez].
"It's difficult for him to come back, as he left here, many club members and people do not want him to come back. From a sporting point of view he would be wonderful, but the other view is also understandable. It is a bit difficult."
Messi also said that, while he is happy to stay with Barcelona for the rest of this career, he does not want a contract which stipulates that has to be the case.
"It is true that Barcelona proposed a contract for life to me, but what I said was that I do not want a contract to bind me," he added.
"I want to be fine to perform, to play and continue fighting for objectives. Being here can be for life, but not with a contract."
Last season was the first time since 2008-09 that Messi and Cristiano Ronaldo were not playing in the same division and the Argentina captain said his Ballon d'Or rival's presence added something to clashes between Barca and Real Madrid.
"It is strange [Ronaldo not being in La Liga]," Messi said. "It was good when Cristiano Ronaldo was there.
"He made the Clasico much more special, he gave more value to La Liga as well"