"It's one of those things where people are well-advised to be careful but aren't always."
He added: "I've certainly never met anybody in the National Party, certainly Young Nats, that's ever expressed those sort of comments to me.
"I went to the Young Nats ball on Saturday night and you can probably imagine the sort of reception I got. And it's pretty well known that my mother was Jewish."
One of the commenters later apologised on the Facebook page.
"For the record, neither me or my friends are racist or have a dislike for Jews. This was a joke between us that got taken out of control, and it's sad to see where it ended up.
"Apologies if anyone got offended by this, and to be clear while a couple of us attended the ball we are not actually members of the young nats and our comments are in no way affiliated with them."
It is not the first time the Young Nats event has received negative publicity.
After the 2012 ball a photograph was posted online of a member who appeared to be making a Nazi salute.
The picture was believed to be an unfortunately-timed photograph with no anti-Jewish intent.