Hundreds of protesters at Parliament House have been told a Labor Government would repeal the Barnett Government's anti-protest laws if they are passed through Parliament.

The Government wants the laws introduced to clamp down on what it claims are extreme protest movements.

The legislation will create a new offence of preventing lawful activity, and will impose heavy sanctions on those convicted under its provisions, with fines of up to $24,000 and jail terms of two years.

Opposition Leader Mark McGowan told 400 people from unions, environmental, Indigenous and community groups that if Labor wins the next election, the laws will not stand.

"They are too broad. They will impact ordinary protests by ordinary people, and that is wrong," he said.

"There can be no compromise, there can be no amendment. There can be no fiddling at the edges. These laws are wrong, they must be stopped and they must be repealed."

Aboriginal elder Ben Taylor told the protest he had been campaigning on the steps of Parliament for 30 years, and would continue to do so.

"We've got to stick together and keep protesting until the day I die," he said.