The Goring Road car park, which has around 40 spaces, closed as business owners were being given notices explaining the decision on Friday afternoon.
A petition has now been launched to get the facility re-opened.
Rob Brown, owner of Shoreline Pet Supplies, said that closing the car park had ‘taken the heartbeat out of the parade’.
“I think the decision is crazy, and our takings over the weekend were half what they would normally be,” he added.
“All of the shopkeepers are fuming because the situation around here with regard to cars is already ridiculous.
“We are being told by the council that there are problems with the surface of the car park but this is not a new thing.
“The customers coming in are having to park up to half a mile away and some are not even bothering.
“It is scary to see an instant change in takings.”
Trevor Jones, who owns The Verandah cafe bar, said: “We have a lot of customers who use that car park and some of them are elderly and cannot walk far.
“It will be total chaos on Mondays when all the deliveries come.
“We have got every facility around here and it is just a nice place to come, for visitors and residents.”
Kelly Charles, shop assistant at Hartleys off- licence, said: “On Saturday, our sales were well down on what they have been.
“The car park provides customer access and when they see that it is closed they carry on driving.
“We are struggling to keep our heads above water as it is, we do not need this.”
A statement from the borough council said: “Recently, local residents have been in touch with us over the condition of the Goring Road car park. Having taken the opportunity to fully assess it, we have decided to temporarily close the car park while a decision is made about its future.
“The funds for resurfacing this car park have been identified in our annual budget and we are working to bring the site up the priority list. Additionally, we’re considering further options for the site’s future, which may include sale.”