The 29-year-old Messi, who retired from internationals last month after Argentina lost to Chile in the Copa America final, is his country’s top scorer with 55 goals.
The five times World Player of the Year has played in three Copa America finals and the 2014 World Cup final, but lost them all.
Cristiano Ronaldo, his frequent rival for FIFA's prestigious Ballon d’Or, recently won Euro 2016 with Portugal, to reignite the debate about which of the two is the world's best player.
“For me, Messi leaving international football does not change anything," Ronaldinho told reporters on Sunday.
"He is still the best football player in the world. The respect I have for him doesn’t change at all...
"And if he really has decided to leave international football then the sport will miss his presence, and so will the fans," added Ronaldinho, who plays in India’s Premier Futsal league.
Ronaldinho, who played at Barcelona for five years from 2003, said he had nurtured Messi when the pair played together at the Nou Camp.
He said the Argentine had followed in his footsteps by helping to guide Brazil forward Neymar at the Spanish champions.
“I am not there to see. But I believe the attention and dedication I had for Messi, is the same thing Messi is doing for Neymar because it’s very important for a more experienced player to share things with younger players,” the 36-year-old Ronaldinho said.
“And that I believe is one of the reasons that Neymar has adapted to the club and their style of play.”
Ronaldinho has been without a club since a two-month spell at Brazilian side Fluminense last year and has not ruled out playing in the Indian Super League.
“I am uncertain but I will go to a place where I feel very comfortable and will consider this possibility (the Indian Super League),” the 2005 Ballon d’Or winner said.
(Editing by Toby Davis)
