The 26-year-old has received judgement for some of his theatrics when being tackled during the World Cup.
Following his side’s 2-0 defeat to Brazil in the last 16, Mexico coach Juan Carlos Osorio accused Neymar of “too much acting”.
Ronaldo won the 1994 and 2002 World Cup as a player with Brazil
But Ronaldo – who is one place and five goals ahead of Neymar in the list of Brazil’s all-time top goalscorers – said: “There are many ways to see football and interpret it.
“I am against all these opinions (on Neymar acting). He is an intelligent player in his movements and on how to defend himself from being tackled.
“I don’t think referees have been protecting him enough. When people repeatedly hit me I would feel a sense of unfairness.
“Criticism is nonsense. TV shows and newspapers just want to fill the space.”
Lothar Matthaus won the World Cup with Germany in 1990
However, former Germany captain Lothar Matthaus held a different opinion to Ronaldo.
When asked about Neymar, he said: “Neymar doesn’t need to act. He’s an excellent player and he has everything a high-level player needs.
“He’s one of the top five players in the world, why does he need to act? It doesn’t bring him sympathy and it’s not good for him.
“(Diego) Maradona wasn’t acting, (Lionel) Messi doesn’t act. (Cristiano) Ronaldo is an actor in a different way but not like this. We need players like Neymar in the game but not like this.”