The protest, involving about 20 people, lasted for three hours in Sutton on Sunday afternoon. Signs were placed in front of the CCTV cameras to temporarily obstruct their view.
A Met police spokesman said: “The protest passed peacefully and no arrests were made.”
Up to 30 cameras in Sutton were thought to have been previously vandalised or removed by more militant campaigners.
Kingsley Hamilton, of Action Against Unfair Ulez, claimed TfL was unable to enforce the Ulez across the south London borough for several hours yesterday.
He told the Telegraph: “Every single camera in the borough is either deactivated or is being covered with a placard.”
Further protests are planned at Biggin Hill on Saturday (February 17), Welling Corner in Bexley on February 20, Chequers Corner in Dagenham on February 24, at Hillingdon hospital for six days from February 25 and at Fiveways Waddon in Croydon on March 3.
Transport for London uses more than 2,000 cameras to check whether drivers of non-compliant vehicles have paid the £12.50 daily levy. Those that fail to pay face a £180 fine.
Mr Hamilton, whose two-year-old son requires hospital treatment for a rare disorder that causes lung infections, said protesters feared the Ulez would be replaced with a pay-per-mile road charging scheme.
He told Sky News: “Ulez is only the thin end of the wedge. Pay per mile is coming if Sadiq Khan gets another term of office, we are quite sure of that. So we are hoping we won’t have Sadiq Khan for another four years.”
However Mr Khan has ruled out replacing the Ulez with a pay-per-mile scheme, saying there is no technology currently available to charge drivers according to the distance travelled and time of day.
“It is not going to happen to my watch,” he told the London Assembly last month. “The pay-per-mile scheme is not on my radar. It is not on the table. It is not something I am going to do.”
Mr Khan expanded the Ulez to cover every London borough in August last year.
Sutton Council fiercely opposed the decision to expand the zone and a petition was signed by thousands calling for its roll out to be delayed.
Mr Hamilton continued: “Even people who have compliant cars had to fork out and get unaffordable loans to buy these compliant cars.
“So it’s all very well saying that people have compliant cars now, but they’ve still got that loan to pay off, that loan that they didn’t need during a cost of living crisis.
He added: “Some of the cameras in the borough have already been deactivated. Obviously, that has nothing to do with us, we are not condoning any criminal activity.”
Protesters have been chopping down Ulez cameras to protest the scheme and one camera was blown up by an “improvised explosive device" in Sidcup in December.
Another Ulez camera in Sidcup was also reportedly cut down on Sunday.
A Met Police spokesman said: “Police are aware of a protest at the Rose Hill Roundabout in Sutton today, Sunday 11 February. The protest passed peacefully and no arrests were made. The group have now left the area.”
A spokesperson for the Mayor of London said: "The vast majority of vehicles – 95 per cent – seen driving in the Ultra Low Emission Zone on an average day are already compliant and will not have to pay a penny.
“The Mayor has been clear that the decision to expand the Ultra Low Emission Zone London-wide was not an easy one, but necessary to tackle toxic air pollution, which is leading to children growing up with stunted lungs and thousands of people in our city developing life-changing illnesses, such as cancer, lung disease, dementia and asthma.
“Causing criminal damage is absolutely unacceptable and all incidents of ULEZ camera vandalism are reported to the police for investigation, with damaged or destroyed cameras swiftly replaced.
“Criminal damage will not stop the ULEZ operating though it could endanger the safety of vandals and the public.”