From later this month, on-street parking in the city will increase by 20p an hour to £1.20. It is the first increase in parking charges since 2004.
NIIRTA chief executive Glyn Roberts said the increase was "excessive".
"While we expected a reasonable increase in existing on-street car parking, a 20% hike is simply too much given the pressure on shoppers and hard-pressed working families," he said. "The reality is that many people who shop in Belfast and other city centres still use their cars and this increase in parking charges is hardly going to act as an incentive to get more shoppers to use Belfast city centre and support retailers."
Transport minister Danny Kennedy said that while he understood the concerns, the increase in fees was unavoidable.
The Department for Regional Development will also decide if it will increase parking fees in 30 other towns and cities across Northern Ireland. Kennedy will report to the Northern Ireland Assembly later this month