Northland, Bay of Plenty, Gisborne, Marlborough, Wellington, Taranaki, Nelson, Southland and Tasman all saw the percentage of their children meeting the standard decline slightly from 2012.
Six regions also had an achievement fall in reading. There were improvements in maths across the country.
Ms Parata told the Herald she was confident those regions that had slipped would rebound.
The data comparing 2011 with 2013 gave a better indication of trend, and that was that improvements were being made.
"That tells a story over three years rather than just one year. In one year, yes, there were declines for some areas. But overall the picture is one of three-quarters of kids being at or above national standards."
Asked about the Government's target to have 85 per cent of children achieving the standards by 2017, she said that was a "stretch target".
National standards describe what students should be able to do in reading, writing and mathematics as they progress through levels 1 to 8, the primary and intermediate years.
The student achievement data is opposed by education unions and there have been concerns about how teacher assessments can vary between schools. But the Government argues it provides valuable information to parents and shows where extra resources are needed.
Yesterday, NZEI primary president Judith Nowotarski said the new results were as unreliable and meaningless as the previous data.
"What the results show is what they have always shown the strong link between socio-economic background and student achievement."