The 57-year-old has been taken to hospital but is understood not to be seriously injured.
Clooney is currently filming TV drama Catch-22 on the Italian island.
Local reports say he was on his way to the set when a car hit the bike he was riding.
A photo published on La Nuova Sardegna website shows a black scooter on one side of the road, with a dark blue estate car facing the other way, at an angle across the central reserve.
The picture also shows a fire extinguisher the bottom of the picture, close to the bike.
The accident is said to have taken place near Costa Corallina, in the province of Olbia, according to Private Mediaset, citing gossip magazine Chi.
He is understood to have received treatment at John Paul II hospital, but NBC News report that he has since been discharged.
Police are said to be investigating the accident.
The drama - which Clooney is both directing and acting in - also stars Hugh Laurie, and is scheduled to be shown on TV next year.
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Clooney has a home with his wife, human rights lawyer Amal, on the Italian mainland, on Lake Como.