Trade Minister Tim Groser said the ban was "entirely appropriate", after global dairy giant Fonterra said some exported whey products including infant formula may contain bacteria that could lead to the potentially fatal illness.
Fonterra has revealed that three batches of whey product have been found to contain the toxic bacteria Clostridium botulinum, which can cause botulism.
China has not officially announced a ban. It said Saturday it had contacted New Zealand's embassy and asked it "to take measures to prevent the products in question from influencing the health of Chinese consumers".
In a statement on its website, China's General Administration of Quality Supervision, Inspection and Quarantine said it had ordered importers to withdraw any contaminated products and called on quarantine officials to step up inspections of dairy products imported from New Zealand.
Groser said the situation with Fonterra was "very serious" and the whey protein concentrate had been exported to Australia, China, Malaysia, Saudi Arabia, Thailand and Vietnam.
"The authorities in China, in my opinion absolutely appropriately, have stopped all imports of New Zealand milk powders from Australia and New Zealand," Groser said on Television New Zealand's Q&A programme. Groser said New Zealand was working closely with China, a major market for New Zealand infant formula exports, and other authorities.
Russia's Ria Novosti news agency reported Moscow was "recalling Fonterra's products, including infant formula and advised Russian consumers not to buy the company's other products".