"We have received a complaint and we are currently analyzing it," said European Commission spokeswoman Lucia Caudet, who also handles internal market issues, without providing more details.
France earlier this year implemented a new law making it harder for everyday drivers to double as taxis, the basis of the Uber business model.
Still facing strong opposition from taxi drivers, French Prime Minister Manuel Valls said this week the practice would be banned completely starting January 1st.
Uber is already fighting the measure in France and last week a Paris business court decided the law could not be enforced until the government had published full details of the restrictions.
San Francisco-based Uber is giving the US and European taxi industries a run for their money by hooking up drivers and passengers through a cellphone application.
The company founded in 2009 is valued at a whopping $40 billion (€32 billion) and says it operates in 250 cities in 50 countries.
However it is battling lawsuits in a string of countries for unfair competition and rising anger from taxi companies over drivers who are not properly vetted and beholden to no one.
New Delhi last week banned Uber from operating in the Indian capital after a passenger accused one of its drivers of rape.
Thailand, the Netherlands and Spain have ruled it illegal and Denmark and Norway have filed complaints against the company.
Belgium on Tuesday said it will launch a investigation into the Uber's tax affairs.