The Sapotaweyak Cree Nation set up two blockades Saturday along Highway 10 to prevent access for workers who are clear-cutting trees near the community.
The line's route calls for it to pass through some of the community's traditional land north of Swan River that is used for hunting and trapping.
Chief Nelson Genaille says RCMP spoke briefly with him and allowed the peaceful protest to continue.
A judge earlier this month denied the First Nation's request for an injunction to stop construction until it said the province properly consulted with the community.
Bipole 3 is a key part of a multibillion-dollar plan to build new hydro dams in northern Manitoba and bring it south to homes and businesses.