Messi told TyC Sports on Tuesday that ‘it would be terrible, for all that Ney means to Barcelona.’
He added: ‘It is OK that he went the way he did, he won an important title here, he won the Champions League, won the Spanish league.
Lionel Messi admits it would be ‘terrible’ if former team-mate Neymar joined Real Madrid
‘But to end in Real Madrid would be a hard blow for us and for Barcelona fans.’
Neymar, who is recovering from a foot surgery after an injury in February, left Barcelona last summer after Paris Saint-Germain paid a record £198m.
But he has been linked with a move to Madrid this summer after just one year in France.
Messi also dismissed the idea he competes with Cristiano Ronaldo to be the best player in the world.
The Argentine continued: ‘I don’t compete with Cristiano. It stimulates me to see them win leagues or to be in the Champions League final.
Neymar has been in France for one season after leaving Barcelona for PSG in a record move
‘I want to win La Liga and the Champions League together.’
‘It’s not an objective to be the best in history. The fact that these things are spoken of about me, well, that’s that. I never set out to be the best, second best, third or fourth.
‘I compete to improve myself year after year, to surpass what I have done before. The more trophies I’ve won at the end of the season, the better, and obviously with the national team, which is something I still don’t have.’
Messi claimed he is not competing against Real Madrid superstar Cristiano Ronaldo