About 350 workers and members of the public gathered with flags and placards at midday.
Unions Otago convenor Andrew Tait told those gathered New Zealand was embroiled in a class war.
"It's clear that Luxon and his wrecking crew are coming after you - they're coming after working-class people as a whole.
"This is class war."
He said the working class needed to unite to fight for workers' rights, particularly for those without unions.
People across the country were protesting today as part of the Fight Back Together - Maranga Ake movement.