The France global, who won the domestic treble with PSG this season, has not yet made his move to the Parc des Princes permanent, having signed on an initial one-year loan deal from Monaco.
He was named in Tite's squad for Russian Federation 2018 as expected this week and all eyes will be on Brazil's first pre-World Cup friendly against Croatia on June 3.
He told TyC Sports: "It would be bad, because of everything he means to Barcelona".
"Ney won important trophies here".
The Paris Saint-Germain forward has not played since February after having surgery on a broken metatarsal bone in his right foot, which he suffered while playing for the Ligue 1 club against Marseille.
"The expectations are very high, not just from the fans but from me as well, that's why this is the biggest challenge I'm facing".
Combine him with the likes of Isco and Marco Asensio, then perhaps Real Madrid's long-term vision is in safe hands too as they go for another Champions League triumph on May 26 in Kiev against Liverpool.More news: AU Sends Health Team to Evaluate Ebola Outbreak in Africa
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And the Argentine admitted seeing his former team-mate at Madrid would be a huge blow.
"It would make Real Madrid stronger".
"If he ends up at Real Madrid it would be a major blow to us. What I miss from Barcelona and about Barcelona is these two [Messi and Suarez], due to the joy we had on a daily basis".
"It's a very hard time, I think it's the most hard I have had because we are so close to my dream, the World Cup".
"I want to win the Champions League every year, to be a league champion every year".
They reached the final of the same tournament in 2015 and 2016 but lost both times and Messi said the successive failures weighed heavily."It's a weight that we carry and we want to overcome it", he said.