Following their shock defeat to Tottenham earlier this month, Madrid face the prospect of finishing second in Group H, which would pit the defending champions against a European powerhouse.
PSG have already qualified for the knockout round with two matchdays remaining and loom as a potential opponent in the last 16, but four-time Ballon d'Or winner Ronaldo is not scared.
"I'm not afraid of PSG," Ronaldo told L'Equipe.
"We're the defending champions, two years in a row, we have to respect that.
"We would prefer to finish first in the group, but the most important thing first of all is qualification."
It has been an unconvincing start to the season for Ronaldo and Madrid.
Ronaldo has only scored once in La Liga this term, while he has six goals in the Champions League with Madrid three points behind group leaders Tottenham.