An insider told Life & Style: "[Clooney's] enjoying spending time with Stacy, but he just got out of a two-year relationship. George isn't ready for anything serious. This fling is purely for fun."
Keibler has not commented on a possible romance with Clooney, but did confirm on Twitter last month that she was travelling in Italy.
She wrote at the time: "I just can't stop eating! I'm in love w Italy, every single part of it… (sic)"
A rep for Clooney is yet to comment on the report.
Clooney split from Italian television presenter Elisabetta Canalis in June after dating for nearly two years.
The actor was recently forced to deny press reports that he planned to debut a new girlfriend at the 68th Venice Film Festival later this month.
Clooney's next directorial effort The Ides of March opens on October 7 in the US and October 28 in the UK.
