Dublin City Council is contacting drivers who were illegally clamped in the first seven months of this year.
They were immobilised even though the correct road markings were not there.
The city council has admitted 26 cars were illegally clamped between Longford Street and Noel Purcell Walk between January and July.
Signage and street markings had been removed to put in an additional traffic lane as part of Operation freeflow.
However, even though they had not been re-erected, Dublin Street Parking Services clamped the cars anyway.
The local authority says it is in the process of contacting the drivers affected to refund them the full fine.
It has also told clampers not to immobilise cars where road markings or street signs are not clearly legible.