Ronaldo, 29, won the La Liga title with Mourniho, but the two have clashed since Mourinho left the Santiago Bernabeu in 2013.
"The relationship between Ronaldo and myself is non-existent," Mourinho told TV1.
"He plays for Real Madrid, I'm the Chelsea manager. You would not find us hanging around together. The relationship does not exist but the memories of his impact do.
"I have to remind myself that he is a goal machine who helped me become a Liga champion, win the Copa del Rey and the Supercopa. I try to keep the best memories of Cristiano Ronaldo with me and I wish him all the best in his career - especially with Portugal but also with his club."
Ronaldo, 29, has been linked with a return to the Premier League in recent weeks, with former club Manchester United reported to be considering an approach for the forward.