RCMP detained five women found near a storage compound for the Coastal GasLink pipeline project on Sunday.
Police said officers came across the car with a purposefully-obstructed licence plate on the Morice Forest Service Road south of Houston just after 5 p.m.
Just prior to stopping the car, they saw three of the women running from the compound to the vehicle and later came across a damaged light generator, police added.
The five were detained briefly, RCMP said.
RCMP later determined they were not responsible for the damage but said an investigation into whether they breached a court-ordered injunction against interfering with the project remains ongoing.