The detentions came amid rising tensions between the government and the ride-hailing company, which culminated last week in a violence-marred taxi strike that blocked roads around the country.
French authorities are frustrated that Uber doesn't pay the same taxes and social charges as traditional taxis, whose drivers have lashed out against what they see as unfair competition.
Uber, meanwhile, argues that the French system is outdated and needs reform to keep up with apps and geo-localisation.
Uber did not immediately respond to a request for comment on Monday but officials last week vowed to keep operating the lowest-cost UberPop service until France's top court rules on it. A spot check of the app on Monday showed drivers available in central Paris.
The standoff reflects larger tensions in France over how to regulate fast-moving technology and stay globally competitive while ensuring labor protections.
Uber has also run into legal problems elsewhere in Europe, as well as in China and India.