Police officers stood at the door of Auckland's Heritage Hotel last night, as about 80 protesters played music and chanted outside the venue.
Sophie Morgan of Auckland Action Against Poverty (AAAP) said the group was protesting the event to draw attention to increased inequality.
She said beneficiaries, the unemployed, and low-wage workers were hit the hardest, while the rich continued to benefit.
"The Young Nats are celebrating while the policies of the National Party continue to wage a war on the poor."
The group had labelled the protest an 'alternative party', and Morgan said the presence of about 20 police officers seemed excessive.