Clooney, 57, was riding the bike at Costa Corallina on the island of Sardinia when he was involved in a collision with a vehicle, according to Italy's TGR Rai Sardegna.
According to Carabinieri officer Alberto Cicognani, the driver of the Mercedes hit Clooney after failing to stop at a turn. Photographs taken by someone passing the scene showed the car's front right bumper damaged and Clooney's bike on its side.
He was taken to John Paul II hospital in Olbia, Italy, for his injuries, but according to NBC News, has already been discharged.
Clooney relocated his family to Sardinia for the summer so he could direct and star in the six-episode mini-series based on the novel by Joseph Heller. George and his wife Amal were last seen out on a romantic evening away from parenting duties on Saturday night in Porto San Paolo.
Clooney has a home on the Italian mainland, on Lake Como.