The 65-year-old Dutchman says that the Portuguese star must not pay attention to the opposing fans, even if they chant the name of the Argentine maestro.
Denmark supporters shouted the Barcelona star's name every time that Ronaldo touched the ball during Portugal's 3-2 victory against the Scandinavians at Euro 2012 last week.
This has been a recurring strategy used by opposing fans in recent times, and Ronaldo could not resist taking a swipe at the Argentine when asked about the chants.
Cruyff has now declared that the 27-year-old should remain indifferent to what comes from the stands.
"To Ronaldo, it must be the same if the fans talk about his mother or Messi," he told reporters.
"If that concerns him, he needs to grow up."
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