McMahon said exact numbers of New Zealanders seeking Irish passports leading up to and since Brits voted out of the EU would be known in the coming weeks.
The spike in Kiwi applications has contributed to an international rise.
Ireland's Department of Foreign Affairs and Trade has seen a 12.5 per cent jump in passport applications this year compared to 2015, and a 21 per cent jump in May 2016 compared to the same month last year.
More than 91,000 people from around the world applied in May - up from 75,000 in the same month in 2015.
McMahon said she believed many of the extra applications were from people trying to secure their Irish passports before the Brexit vote.
Devonport woman Kate O'Rourke is applying for Irish passports for her whole family.
She gained an Irish passport through her husband Gavin's heritage, although both of theirs have lapsed. They lived in Dublin for three years from 1999 to 2002.
O'Rourke said she wanted her kids - Saoirse, 13, Rona, 11, and Caoimhe, 8 - to have them in order to give them freedom when they get older and begin to consider work and study options abroad.
"[Brexit] has motivated me to shift that up the priority list because I would imagine there would be a lot of Irish and English people looking to position themselves, and the offices might be overloaded.
"The two older kids have Irish citizenship, but we've been slack with the youngest. We'd better be quick and get her her citizenship."
Meanwhile, the classic Kiwi OE isn't under threat despite Britain's ditching the EU, according to Acting British High Commissioner Helen Smith.
"The UK must now consider and negotiate new arrangements with the EU, this will take time and there will be no immediate changes."
