About 40 protesters called on the Government to abolish 90-day work trials and to stop time restrictions relating to unpaid holiday pay and a six-year statute of limitations.
In March, the Ministry of Business, Employment and Innovation revealed up to 700,000 employees could have been underpaid because of errors in compliance with the Holidays Act.
Unions Otago convener Fiona Matapo said a Treasury report on 90-day workplace trials released last month showed it had had "no positive impact'' on "We know from the Government's own research that the 90-day trials have not resulted in an increase in employment.
"What it has caused is increasing marginalisation of workers.''
The protest included representatives from the Rail and Maritime Transport Union, Unite Union, E tu, the New Zealand Nurses Organisation and the New Zealand Public Service Association.
The New Zealand Nurses Organisation southern educator, Jenny Crighton, said that the 90-day trial, which was contained in the Employment Relations Act, was an "appalling way to treat people, especially immigrants''.
Mr Woodhouse's office was closed during the protest. In a statement read by his secretary, Cindi Ewart, he said the Government had "no plans'' to repeal the 90-day trial legislation.
When asked if Mr Woodhouse had any comment on holiday back pay, Ms Ewart said no.
"I don't know that he knows what they were protesting about,'' she said.
