The NSW Parliament has passed tough new punishments for protesters the state government says wish to wreak "economic chaos" on Sydney.

Under legislation that cleared both houses today, people could be fined up to $22,000 and/or jailed for a maximum of two years for protesting illegally on public roads, rail lines, tunnels, bridges and industrial estates.

The new offence applies to ports in Newcastle, Port Kembla and Port Botany, but the government says it intends to add more facilities.

Attorney-General Mark Speakman said the laws applied to activities that "shut down major economic activity".

It comes after a string of demonstrations by climate activists last month disrupted operations around Sydney's Port Botany, the largest container hub in NSW.

Members of Blockade Australia staged protests on bridges, roads, freight rail lines and a crane to call for greater action on climate change.

This morning, four people were arrested after blocking peak-hour traffic on the Princes Highway in Sylvania.

Fireproof Australia has claimed responsibility for that incident, which saw traffic blocked by people holding banners across the road.

Mr Speakman said the state government was "on the side of climate change action" but could not stand for "a handful of anarchist protesters who would wish to bring this city to a halt".

He claimed the government led by Dominic Perrottet was "potentially the most ambitious government in Australia when it comes to real climate change action".

The new laws were not designed to block action such as the NSW Nurses and Midwives Association's mass strike yesterday, Mr Speakman said.

"What we are stopping, or criminalising even further, are protests that shut down major economic activity," he said.

In a speech to parliament, NSW Labor leader Chris Minns said the opposition supported the legislation as it was important "to the safety and security" of NSW.

"It is shameful to think that it's appropriate to disrupt the lives of ordinary people as they go about their business in the pursuit of your own particular aims," he said.

The Greens opposed and tried to amend parts of the bill, which was eventually passed with support from Labor and the crossbench.

The Greens say the laws undermine the right to peaceful protest, and targeted those whose causes did not fall into narrow union-led actions.

Greens MLC David Shoebridge claimed in a statement the legislation was designed by the government "to jail their political opponents".

"That's not just bad public policy, it's deeply anti-democratic," he said.

"This move to target political and environmental campaigners may well be in breach of the constitutional protections for political communication and we anticipate a court challenge on them very soon."

Metropolitan Roads Minister Natalie Ward said the laws would punish people who wanted to "hold the state to ransom".

"If you want to protest you either do it lawfully or you face the consequences," she said.