Amara Miller, who plays the 10-year-old child of Clooney's land baron in the family drama, told Us Weekly: "Let me just say, he wouldn't be good as a father. He wouldn't be the best as a father."
She continued: "George likes being an adult. George has fun being an adult, and I don't think he would like having kids. I know that he's not planning on having kids any time soon."
But she added that Clooney was "so fun".
"He was just a really phenomenal person to work with," she said. "(But) we don't really keep in touch any more. He's George Clooney... No one really keeps in touch with him any more!"
Clooney, 51, is currently dating former wrestler Stacy Keibler, 32, after splitting with Italian actress Elisabetta Canalis in August - reportedly because Canalis was keen to tie the knot.