The billion-dollar company said the rules would "threaten the livelihood of thousands of drivers", reducing their numbers and thus increasing the waiting times for users in an email directly appealing to customers and authored by Uber's top boss in London, Tom Elvidge.
The new rules were given the greenlight by TfL in March following a long-running and public battle between the two sides and London's black cab drivers.
At the time, Uber welcomed the result of TfL's review after it dropped proposals that would enforce users to wait five-minutes after ordering a cab, even if there was a car available instantly.
Now, Uber is urging customers to email the newly elected Mayor of London Sadiq Khan to demand the rules - formulated after a comprehensive consultation conducted by TfL under the former Mayor Boris Johnson - are looked at afresh.
It's understood that while the broad conclusions of the review are accepted, the finer details and exact form the rules will take, hammered out over the last few months, are more onerous than Uber had been expecting.
Uber has called into question the English language requirement rule - which it claims is harder than the test for British Citizenship and more than the requirements for becoming a Tube driver.
It has also called out a requirement for part-time drivers to have costly full-time commercial insurance even when they're not driving, as well as the need for Uber to tell TfL of any changes to its app, which it argues would slow down the roll out of new features.
The latter two rules now already apply while the rule on English language tests will come into force from 1 October.
Those who receive the email are asked to click on a link to email the Mayor, leading to an already written reply which even signs a users name at the end automatically.
I agree with you that it’s vital London remains open and that everybody has the chance to succeed, whatever their background.
However, I’m concerned that new rules from Transport for London will threaten the livelihoods of thousands of licensed private hire drivers in our city.
Forcing all drivers from non-English speaking countries to pass a £200 two-hour written English exam goes way beyond what’s needed to help Londoners get from A to B.
Making part-time drivers pay for costly commercial insurance in the months when they’re not working is also unnecessary and could force some to give up driving for a living.
Nor does it make any sense for TfL to demand to be told before Uber makes changes to its app.
Please look again at TfL’s plans. Let’s keep London open.
Uber also appealed to the Mayor in the wake of Brexit and in light of the "Open for Business" campaign, seeking to bolster business in the capital.
"Uber has already invested £100m in London - and we plan to invest even more in the future. It’s why we support the new Mayor’s Keep London Open campaign," it urged customers.
"But bureaucratic new rules from Transport for London send the opposite message and threaten the livelihood of thousands of drivers."
A spokesperson for the mayor of London said “[The Keep London Open campaign] does not deflect from [Khan’s] determination to create a vibrant taxi and private hire market, with space for all providers to flourish, while driving up standards ... to improve safety and the quality of service.”