Theresa May said Transport for London's decision to stop Uber operating in the capital has "damaged lives" and called the ban "disproportionate".
Last Friday, TfL denied Uber's application to renew its licence to operate in London, effectively banning it from running its business in the city.
TfL cited a string of failings which it said meant Uber was not "fit and proper" to hold the licence, accusing it of "a lack of corporate responsibility in relation to a number of issues which have potential public safety and security implications".
The decision was supported by London Mayor Sadiq Khan who said Londoners' anger "should be directed at Uber". Khan is also chairman of TfL.
In an interview with BBC London ahead of the Conservative Party conference next week, May said "at a stroke of a pen, what the mayor has done is risked 40,000 jobs and of course... damaged the lives of those 3.5 million Uber users".