The First Minister said yesterday a proposed tax on large retailers must not be a "blunt-edged instrument which could have unintended consequences".
The planned levy put forward by Peter Robinson's DUP colleague, Finance Minister Sammy Wilson, would draw a sum from the profits of companies such as Tesco and Asda to pay for greater rate relief for indigenous firms.
Mr Robinson, speaking at the Retail NI conference at the Stormont Hotel, said that such a "holiday" for smaller retailers, "has to help those in need rather than give a payday to those who are not".
"We must not reduce the cost for one group in order to increase costs for another," he said. "It will not be allowed to proceed if the harm would be greater than the good."
But he added: "Some larger stores do find it easier to lobby than small high street stores."
Meanwhile, another speaker, Alex Gourlay, chief executive of the health and beauty division at Boots, said that while retail provision in Belfast needs to have a better balance, the proposal needed more thought.
"Big banks should also be contributing to this levy," he said. "Is it a good idea for big businesses to support small businesses? Absolutely, but let's do it properly. We need to adapt on the high street in order to change and prosper, there needs to be a civic pride and business-led partnership."
He also said that city centre car parking prices are becoming an issue for people with tight budgets.
"Parking charges can be offputting in this economic climate," he said.