"We impounded 18 vehicles of Ola and Uber yesterday for over-charging and permit violation," Rai told reporters here.
"The action was taken after commuters complained on the helpline provided by the Delhi government," Rai said.
Chief Minister Arvind Kejriwal on Monday threatened "strict action" in the wake of complaints of "surge pricing", a technique used by the cab aggregators to hike the fares due to higher demand.
The Delhi government had said the erring taxis would be impounded and their drivers' licences seized.
After Kejriwal's threat, Uber and Ola suspended their surge pricing.
Monday was the first full working day after the start of the second round of the odd-even traffic scheme which forced many motorists who did not use their cars to go for taxis.
Under the odd-even scheme, which is aimed at battling pollution, petrol and diesel driven vehicles with even registration numbers can ply only on even dates and those with odd numbers on odd dates.