The Real Madrid ace wants to leave Spain and people close to the player says that he still holds United close to his heart, Sky Sports said.
Reports suggest United will offer Spain keeper David de Gea, 26, and £174m in exchange for the Portugal star.
United remain cautious about getting involved in a transfer merry-go-round and club officials believe that the Portuguese legend will eventually decide to stay in Spain.
The players’ advisers, though, have been told to find a way out of Spain for Ronaldo, who is apparently upset after he was recently accused of tax evasion amounting to £13m.
The problem for Ronaldo is that very few clubs could afford his wages on top of what would be a massive transfer fee.
PSG are said to be interested in signing him while AC Milan’s new Chinese owners have also reportedly been in contact with his agent Jorge Mendes.
Chelsea are also rumoured to be interested.
A move to the Chinese Super League is also a possibility, although Ronaldo is said to want to carry on playing in Europe.