The actress plays the evil Queen Clementianna in the film adaptation of the Brothers Grimm's Snow White story.
"I think my kids are too young to see the movie, considering my part," she told Us Weekly.
Roberts admitted that she enjoyed playing Queen Clementianna because she "could go off the rails in any direction at any time", but said she is not like her evil role.
"I am happy to announce that [the Evil Queen] is not inside me!" she said. "But without naming names, I drew [how to play the part] from a couple of people I know."
Roberts, who plays a woman upstaged by a younger beauty in the film, has previously revealed she will not use Botox again because she wants her kids to "know what emotion I'm feeling at the exact moment I'm feeling it".
Mirror Mirror was released in US cinemas on March 30 and will be released in the UK on Monday, April 2.
Watch a Digital Spy exclusive scene from Mirror Mirror below: