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.
Sao Paulo: Brazilian striker Neymar said getting fit for the World Cup following surgery has been the biggest challenge of his career and he is also anxious about how his injured foot will respond to top-class competition.
"It would be awful because of what Ney means to Barcelona", Messi told Argentina's TyC Sports on Tuesday, reports Efe news agency.
"Ney won important trophies here".
Neymar's impressive performance has triggered talks about a potential move to Spain again, this time to the Spanish capital to join Barcelona's arch rivals Real Madrid ahead of next season.
Paris Saint-Germain's Neymar Jr has admitted he is "scared" as he closes in on a competitive return to the pitch with the FIFA World Cup with Brazil looming large. "And on a football level, it would make Madrid much stronger than they already are".
Messi, the five-time World Player of the Year, also said he was looking forward to the tournament in Russian Federation and was targeting at least a semi-final place with Argentina.
"But right now, I'm a coach of these players, and I value what they have done and what they are doing, whenever we have difficulties, they are the ones who are fighting. What I miss from Barcelona and about Barcelona is these two [Messi and Suarez], due to the joy we had on a daily basis".
"I faced him with Monaco [in the Champions League in 2016-17]", he told Le Parisien. "It's what we all want".