Mr Johnson said his company made a number of submissions opposing the kiwi.nz domain name but they were ignored.
"We still await an explanation on how the creation of the .kiwi.nz domain is in the best interest of the internet in New Zealand, when clearly there will be significant public confusion."
He said internetNZ displayed a lack of common sense in approving the name.
The .kiwi name is yet to be approved by the global company ICANN (Internet Corporation for Assigned Names and Numbers).
On its website, internetNZ said the domain name fitted with its criteria for names, including that it did not "conflict with, duplicate or cause confusion about, any existing second-level domain and is a useful addition to the current DNS (Domain Name System) hierarchy".
The company's domain name commissioner, Debbie Monahan, told APNZ that the .kiwi name was not in existence yet and it also fell under a different type of domain to the .kiwi.nz name.
"You have two different sorts - generic top level domains, like .com and then you have country code top level domains like .co.nz."
InternetNZ set its own policies for the .nz names and when it considered approving names, it could not take into account domain names from other levels, Ms Monahan said.
She did not think people would be confused by the two names.
"If it's successful I think .kiwi definitely has got a place, but I don't necessarily think it's going to be confusing."
The .kiwi.nz name will be available from September 11.
If the .kiwi name is successful it will be available from early next year.
