Despite the diplomatic achievements, McCully said getting out of step with major western allies over Iran would be bad for NZ's reputation.
"For example, one sure way to kill the conversation on an FTA [free trade agreement] with Europe would be to get out of alignment with them over either Iran or Russia," he said.
A spokesman for McCully said it was too early to provide any more details on the trade mission.
Stewart Germann, chairman of the New Zealand Middle East Business Council, said in July that many of the council's member firms - which include Fonterra and Tegel Foods - saw Iran as a "significant market for potential business development".
*An earlier version of this article said New Zealand Trade and Enterprise chief executive Peter Chrisp had visited Iran recently. NZTE says Chrisp has never visited Iran.
Potential for Growth
• New Zealand exported around $163 million worth of commodities, mostly dairy and other animal products, to Iran last year.
• Exports to the United Arab Emirates were worth $916 million in 2014, despite the UAE having a population of less than 10 million compared with almost 80 million in Iran.