Can's new £89m teammate was sent off for Juventus in the 29th minute during their 2-0 win away at Valencia in Group H of the Champions League.
Ronaldo walked off the field in tears after the incident with Jeison Murillo, leaving Can angered by the controversial dismissal.
"That's supposed to be a red!?" Can told DAZN.
"I just heard that he said it was because of hair pulling. We're not women, we're playing football.
"If you're giving that as a red card, you can be sent off for any foul. One hundred per cent, that is not a red card."
Can left some fans furious with his heated comments as many labelled the German midfielder 'sexist'.
Jack Gallagher (@calciolovesjack) tweeted: "Very ill-advised, and pretty sexist, comment from Emre Can."
Beatriz (@b1aqueen) said: "AWFUL! sexist as hell."
Juventus will be without Ronaldo for their next Champions League group match against Young Boys on October 2.