The 28-year-old has long been linked with a move away from the Bernabeu and he admitted in September last year that he was “unhappy”.
Manchester United have been working on a deal to sign the Portugal international, but face strong competition from PSG.
“With strong players, it is normal that big teams are interested,” Ronaldo’s agent Jorge Mendes told Radio Mana Mana.
“Paris Saint-Germain is a possibility.”