Labour leader David Shearer said the policy was necessary to give Kiwi first-home buyers a helping hand into the market.
"We've found properties from Auckland to Invercargill that are being marketed to offshore speculators. There is no benefit to New Zealand in selling our homes to speculators who have no intention of living here.
"That can only increase demand, and help drive up prices."
Mr Dear said while he dealt with a range of investors looking at coastal holiday homes, waterfront apartments in Tutukaka and sections in Matapouri Park, numbers had dropped off since the global financial crisis.
"There's been a lot less of late."
He was in "two minds" about whether Labour's policy was needed.
If larger farms and pockets of land were bought by overseas investors, Kiwis could lose some control. But commercial investment brought money and different people into the area.
"If Labour gets in and they implement the policy, it certainly will make some changes to coastal areas. I don't think it would have a big impact but it would have an impact."
Northland housing sale figures released by the Real Estate Institute of New Zealand show the number of houses sold in June 2013 rose to 157, compared to 153 in June 2012.
However, the median property price dipped, from $308,000 to $293,000 over the same period.
The Labour policy is already drawing mixed political reaction and has been labelled anti-Chinese.
Prime Minister John Key said there was a limited number of foreign home buyers, and Labour's policy would have little impact on the market.
"The reality is that not that many people come in and buy properties that aren't either permanent residents or aren't going to take up personal residencies."
Housing Minister Nick Smith said Labour was putting the blame for the housing shortage on foreigners.
"There's no evidence that overseas buyers are having any discernable effect over house prices."
New Zealand First and the Green Party are backing the plan.
APNZ
