The Brazilian forward left Barcelona in 2008 and admitted that he laments the fact he did not play longer with the four-time Ballon d'Or winner.
"The only regret is not playing more seasons with Lionel Messi, he is my good friend," Ronaldinho told the Daily Mail.
"I could see even at a young age he was going to be the best. It was exciting to see this kid who could do things most players can only dream of."
The 32-year-old also said that he did not resent the fact that he never played in the Premier League, pointing to his trophy haul as proof of wise career moves.
"Do I regret not playing in England? No, because I have played for some of the biggest teams in the world and won everything," he added.
Ronaldinho will start in Wednesday's friendly with England at Wembley.