The former professional wrestler has been the subject of speculation since pictures emerged that seemed to show a baby bump, reported Sun Online.
But the 32-year-old beauty insisted the rumours were "100 per cent false" and posted a picture on Twitter to show she is completely bump free.
The blonde star showed off her six-pack as she posed in white crop-top and big shades.
Keibler and Clooney are currently on a romantic break to celebrate their one-year anniversary in Italy.
