The pair became an item in August last year, and have stayed together despite recent rumours of a split.
The Sun reports that when asked about the couple potentially marrying, Keibler responded: "That is not on my radar at all.
"I'm definitely the girl who doesn't talk about that kind of stuff. I'm not really interested in thinking about marriage or kids at all."
Clooney broke up with previous girlfriend of two years Elisabetta Canalis just days after she announced her interest in the pair one day getting married.
Clooney is currently planning to script, direct and star in World War II drama The Monuments Men alongside Paul Giamatti, Cate Blanchett and The Artist star Jean Dujardin.