Real Madrid forward has contacted Barcelona's Neymar, telling him to reject Paris-Saint Germain and wait for Manchester United.
Neymar is reportedly eager to leave Barcelona after some media outlets claimed the Brazil international was fed up playing in teammate Lionel Messi's shadow since joining the club in 2013.
Spanish sports newspaper Diario Gol claims Ronaldo has reportedly got in touch with Neymar and told him to hold off interest from PSG, who are reportedly willing to break the world transfer record in order to sign the former Santos man.
United have also been touted as a potential destination for Neymar, with the Red Devils showing in recent transfer windows that they are financially strong in securing deals for midfielder Paul Pogba and striker Romelu Lukaku.
Ronaldo reportedly contacted Neymar through WhatsApp, telling the 25-year-old he would be dropping down a number of levels in order to play for PSG, whose record in Europe is incomparable to Barcelona's.
PSG have failed to win the Champions League while Neymar has already tasted success in the competition with Barcelona before, scoring in the final of the 2014-15 edition of the competition as the Catalan giants beat Juventus 3-1.
Ronaldo apparently pointed out that Ligue 1 currently lacks the appeal of Spain and England's top divisions and has urged Neymar to hold out and sign for his former club in the future instead.
Neymar has scored 105 goals in 186 appearances for Barcelona since joining the club, winning two La Liga titles and three Copa del Rey cups.