Spokesman Billy Dain said logging trucks had been turned away from the Ellery forest, 40km northeast of Orbost, since 3.30am on Wednesday.
One woman sat in a wooden structure, 8m above an access road, while two others were on a 30m-high tree platform connected to logging machinery, he said.
Mr Dain said Ellery contains wet old-growth forest and rainforest and that logging had a severe impact on endangered species such as the sooty owl, long-footed potoroo and powerful owl.
"These actions draw attention to the fact that the Government is still not listening to the people," he said.
"It's time for Premier Steve Bracks to end all old-growth logging immediately."