The prime minister is at the brunt of criticism over a police action in northern B.C.
Dozens of demonstrators prevented him from speaking about treaty issues at a building in Ottawa today.
They were expressing their opposition to the RCMP arresting 14 activists who were blocking a forest road on Wet'suwet'en territory.
Hereditary chiefs say that TransCanada Pipelines officials are trespassing on their land by trying to develop the Coastal Gaslink pipeline.
The Mounties were enforcing an injunction obtained by the company last month in B.C. Supreme Court.
Justin Trudeau ended up delivering his address in another building.
Meanwhile, environmental activist Paul Watson has accused Trudeau of having "declared war" on five Wet'suwet'en bands in B.C.
Watson used this term in a Facebook post with the headline "The Jack Booted Thugs Are Invading the Lands of the Wet'suwet'en People Now!"
"The RCMP have been ordered to enforce this ruling on behalf of the companies with the full backing of Prime Minister Justin Trudeau who before the election pledged to defend indigenous rights," Watson wrote.
If the pipeline is completed, it will carry natural gas from northeastern B.C. to Kitimat, where it will be converted into liquefied natural gas for export to Asia.
The company says it has secured agreements with 20 elected First Nations councils along the pipeline route.
The hereditary chiefs, on the other hand, maintain that the elected councils' authority is restricted to reserves and does not apply to traditional territory where the Gitimt'en clan had set up a checkpoint.
There's another blockade set up by the Unis'tot'en clan on a bridge crossing the Morice River.
They say that under article 10 of the UN Declaration on the Rights of Indigenous Peoples, they should not be forcibly removed from their land or territories.
The Delgamuukw decision in the Supreme Court of Canada in 1997 acknowledged the existence of Aboriginal title on Wet'suwet'en lands, noting that this was not extinguished when B.C. joined Confederation in 1871.
Today, protesters in Vancouver made that point in a march in downtown Vancouver.
"I want to say to Prime Minister Trudeau: welcome to battleground British Columbia." Grand Chief Stewart Phillip said.
Below is some video footage of the local demonstration.