According to a statement by the Atlético fans on Twitter, the fans are expressing absolute opposition to the possible signing of a contract with Ronaldo, because Ronaldo represents the opposite of the values that are the hallmarks of Atlético.
It is noted that the fans are asking the club to abandon the idea of signing a contract with the Portuguese footballer.
On July 26, Atlético President Enrique Cerezo said it was almost impossible for the 37-year-old to join the club.
Manchester United's contract with Ronaldo is valid until June 2023.
Manchester United finished sixth in the Premier League and will not be able to take part in the Champions League.
Earlier, Jorge Mendes, Ronaldo's agent, held talks with Manchester United.