Economists say record prices for exports could be prompting a backlash from customers.
The pace of growth in global prices for commodities has slowed further, though it did set another record high in May.
The ANZ Bank's commodity price index rose 0.3% in the month, the ninth consecutive monthly gain, but the smallest gain since September.
With the start of the kiwifruit season, prices jumped by nearly a fifth compared to the same period a year ago, while skins, skim milk powder, lumber, cheese and sheepmeat all rose.
In contrast, apples, beef, whole milk powder, aluminium, butter and wool all declined.
ANZ economist Steve Edwards says high prices and rising global supply will sap momentum.
He says an easing in the price of dairy goods - which makes up 40% of the index - is due to increased production and some consumer resistance.
Goldman Sachs economist Philip Borkin says volumes remain at historically high levels, however a consumer backlash can't be discounted in the latest figures.
"You've seen that in New Zealand, where dairy prices have risen and people cut back on their consumption of cheese and those types of products, so that's a factor we need to be aware of."
Council of Trade Unions' economist Bill Rosenberg says exporting just raw materials is potentially a problem for New Zealand, and export industries need to be better diversified.