The protest, at the Crown St offices of global services company GHD, coincided with protests at the engineering and resources company's other offices Australia-wide.

Some of those arrested said company management, along with police, forced them to delete photos and footage taken at the protest, in order to avoid charges.

The protesters, from the group Stop Adani Illawarra, urged GHD to reconsider its involvement with the Carmichael mine in central Queensland, which in June received its final government approval.

Protesters said there were 10 arrested but police said the actual figure was eight.

They were released without charge after being cautioned and ordered to stay away for eight hours.

"There was a heavy police presence, with authorities and GHD management demanding photos and videos taken during the action be deleted and not passed on to media," Stop Adani Illawarra spokeswoman Rada Germanos said.

Ms Germanos said they wanted GHD to follow through on its website claims that it wasn't to support environmentally responsible operations - so they held a meditation session.

"We've been here leading a meditation session, guiding GHD through a process of mindfulness - to take a breath in, consider their company's reputation and relationship with the environment, and to breathe out and let Adani go," she said.

GHD head office was contacted for comment but did not respond.

"GHD is putting their reputation on the line by refusing to distance themselves from Adani's climate-wrecking project," Ms Germanos said.

"This company could lead the way to a future powered by renewable energy, green jobs and climate-friendly infrastructure that are part of the climate solution for communities both in Queensland and the rest of this continent."