Barca players including captain Andres Iniesta, striker Luis Suarez and defender Gerard Pique have publicly urged Neymar to stay at Camp Nou, but the 25-year-old's future became further clouded in doubt following a training-ground bust-up with Nelson Semedo on Friday.
And the 2002 World Cup-winner has advised his compatriot to follow his instincts when it comes to his own career.
"I can only tell him to follow his heart and be happy, to do things that his heart tells him," Ronaldinho told a media conference.
Neymar is said to be interested in the move to PSG after growing unsettled in Catalonia and eager to escape the shadow of illustrious team-mate Lionel Messi.
Messi and Suarez are reported to have spoken directly to the player to persuade him to stay but Barca president Josep Maria Bartomeu admitted this week that Neymar's future would be out of the club's hands if his buy-out clause was met.