Neymar swapped Camp Nou for Parc des Princes in a world-record €222m ($253m, £200m) move back in August 2017.
The 26-year-old spent four successful seasons at Barca, winning La Liga twice and the Champions League once, but a desire to step out of Messi's shadow is believed to have motivated his unexpected exit.
Speculation persists that Neymar could yet seek a return to the Blaugrana and his Brazil team-mate Arthur, who linked up with Spanish champions at the start of the season, said this week he was "praying" for the rumours to become reality .
Messi shares a similar view but holds reservations over the likelihood of PSG sanctioning the transfer.
"I see it as complicated," the Barca captain said in a wide-ranging interview with Marca .
"We would love him to come back for what he means, both as a player and for the locker room.
"We are friends, we have lived very nice moments, others not so much, but we have spent a lot of time together. However, I find it very difficult [for him] to even leave Paris.
"PSG are not going to let Neymar get taken away."
The five-time Ballon d'Or winner also still harbours hope of a future reunion with Pep Guardiola.
Guardiola, now in charge at Manchester City, has previously claimed his only route back to Barca would be as a youth coach, but Messi would appreciate the opportunity to play under the Catalan once more.
"Although it is difficult, I would like to work with Guardiola again," he said.
"He is one of the best coaches in the world. That's why I would like [him to come back], but I'm telling you that I see it as complicated."