Messi announced on Wednesday that he plans to take his talents to South Beach after his contract with the French champions expires at the end of this month.
"I already knew... Messi is one of my best friends, it's a gift that football has given me to have the opportunity to meet him, play with him and then establish such a beautiful friendship," Neymar said in an interview with ESPN Brazil on Sunday.
"I told him he's going to be very happy for the city, for the lifestyle and for the opportunity to live and play here in Miami.
"I'm sure Leo is going to change the league in the United States. I think the league is going to be much more popular, so everybody has to take advantage and enjoy watching him play, because unfortunately nothing lasts forever," he added.
The Brazil international and Messi's former Barcelona and PSG teammate visited basketball player Jimmy Butler in Florida ahead of Friday's Game 4 in the NBA Finals.
Butler, a six-time NBA All-Star, also said he is excited about Messi's move to Inter Miami and that the Argentine World Cup champion will do a lot of good for U.S. soccer.
"Now that he's here, I think all the football fans around the world are going to come and get a chance to see him compete. I'm glad he's here," he told reporters last week.
