Residents had said the design of the Hardwicke Street facility would impact on their quality of life.
They had urged the planning committee to defer its decision earlier this month so that amendments can be made.
The town hall is keen to bring the disused site into play with the Market Hall car park set for demolition as part of the Markets Quarter redevelopment.
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The application is to use the car park for a three-year period.
Friends of St Ignatius Square representative Nick Millband had suggested the plan should be changed to a 59-space car park with more defined boundaries between the rear perimeter of residential properties.
He said: “We’re not asking for much. It’s a conservation zone, three years is a long time for a conservation area not to have any landscaping, it’s a totally inappropriate usage. Put some trees in. Are 17 car parking spaces worth more than the health and wellbeing of residents?”
A council report reads: “The proposed use of the site as a temporary car park would tidy up and bring a vacant site back into short term use without hampering the long-term potential.”