While all their classmates dashed out to see the "Pretty Woman" star face off against Lily Collins in the 2012 film, young Hazel, Finn and Henry had to stay at home.
Roberts tells U.S. breakfast show Today, "All of the kids in their class saw it, and I wouldn't let them see it, so they felt that they were being penalized for being my children.
"(I said), 'Well, I'm not very pleasant in that movie. I don't want to scare you.'"
Watch the "Mirror Mirror" trailer: