The taxi inspection was one of two joint operations carried out by the RTA with Dubai Police and the General Directorate of Residency and Foreigners Affairs.
The second, in July, focused on fare evasion on public buses, during which almost 700 offences were detected in a six-day operation.
The inspection into unlicensed transport activities took place from June 15 to 30 in the Al Ghubaiba area and uncovered in 39 separate offences, the RTA said.
There were 22 cases of passengers being transported in illegal vehicles with a further 17 offences for the promotion of unlicensed taxi services.
Six vehicles were seized during the operation, which was in Al Ghubaiba because it is known for a high demand for buses, taxis, and Dubai Metro, the RTA said.
The operation focusing on fare evasion, between July 17 and 22, detected 693 incidents across the emirate.
There were 591 cases of using public transport without paying the due fare.
The RTA said there were 33 incidents of failing to provide a nol card upon request, with five cases involving the use of an invalid card.
There was one case of obstructing the work of RTA inspectors and 61 incidents of not following the instructions for the use of public transport and facilities.