Ahead of this week's climate change summit in New York, activists rallied across the World calling for greater respect for the environment.

But in the New South Wales Blue Mountains, activists have disrespected a sacred Aboriginal place and world heritage listed site at Echo Point look-out.

"Nothing can explain the heartache that this has caused to Aboriginal and non-Aboriginal people of the Blue Mountains," said Gundungurra elder Sharyn Halls.

"You’ve got to do your homework first and look at what you are doing, it’s just so disrespectful," said Member for the Blue Mountains Roza Sage.

The increasing deterioration of the Three Sisters led to the prohibition of climbing by NSW National Parks and Wildlife Service 14 years ago.

"It's illegal, there are fines connected with it and it is against the national parks act to actually climb on the sisters," said Ms Halls.

Global Climate Activist Group 350.org co-ordinated the day of action, but told NITV News the banner posted on the culturally and environmentally sensitive site was not a sanctioned event.

"As far as I'm concerned the people who put that message up there were trying to put a message up there to do with climate action but they've created an environmental vandalism event themselves so I don't think they've thought through what they were doing properly," said Ms Halls.

"Irrespective of what their political persuasion or ideology is, it is just not right as well as being illegal to put that up there on that area and hopefully it won't encourage others to do that same thing," added Ms Sage.

National Parks and Wildlife commissioned the sign to be removed by a climber 24 hours after the incident was reported.

But that was too late in the eyes of Ms Halls who is seeking a public apology from the campaigners.

"I'd like them to come forward and apologise to the Aboriginal community and the non-Aboriginal community and pay the fines of getting that banner down," she said.

The Office of Environment and Heritage is looking into the matter.

Blue Mountains MP Roza Sage says legal action will be pursued if enough substantial evidence is put forward.