NSW Police Commissioner Karen Webb has taken Rising Tide to the Supreme Court in a bid to stop next month's Newcastle harbour blockade from going ahead.
The event, scheduled to take place between November 19 to 28, is expected to attract 10,000 participants from across the country.
It coincides with Rising Tide's campaign to stop coal exports from the port by 2030.
About 1500 protesters took part in last year's 30-hour blockade.
Organisers claimed the event stopped as many as eight ships carrying up to half a million tonnes of coal leaving the port.
More than 100 people who were arrested after they refused to leave the water when the protest permit expired.
This year's event has attracted artists including Midnight Oil's Peter Garrett, John Butler and First Nations rapper Dobby. But it has also resulted in the cruise liner cruise ship Silver Nova scrapping plans to visit the port November 24.
Greens MP and spokesperson for climate change and justice Sue Higginson described the NSW Police Supreme Court appeal as an "expensive, unnecessary and retrograde step."
"It sends a very dangerous message to the people of NSW who care about the right to protest and those who want the Government to do more about climate change," she said.
"Rising Tide have been steadfast in their responsibilities around organising this iconic climate protest event. They have approached the police in good faith seeking to work with them to ensure the event is safe and orderly and not only have they been let down they are now at the other end of a legal case. When the state fights the people in this way it says that something is very wrong with the administration of our democracy."
Speaking in Newcastle on Tuesday, Premier Chris Minns said the blockade would damage the state's economy and its ability to transition to a clean energy economy.
"I don't want to be antagonistic about it, other than to say that if you block that port and put obstacles in the way of industry, it prevents and hurts our ability to transition the economy to get the kind of revenue we need to invest in vocational centers like this one (Tafe Centre of Excellence) and to ensure that the economy is better tomorrow," he said.
"At the end of the day, my responsibility is still to the NSW economy and ensuring that the Hunter in Newcastle have a future.
"The state's biggest export as of today is still coal. I know people don't like saying that. They don't like hearing it, but that's the truth and until we get other industries up and running and pumping in the Hunter that is going to be a key source of revenue to transition that economy, and I'm not switching it off tomorrow."
But Ms Higginson said protests such as the harbour blockade were essential to a functioning democracy. This one has the support of so many people. Icon Australian author Tim Winton just last week was encouraging people to get to the protest and the line up of acclaimed artists who will be performing is testament to support and the need for this gathering," she said.
"It appears to me the "People's Blockade of the World's Largest Coal Port" will go ahead, regardless of what the police do in court, because the State can not stop people from coming together."
