Mike Bradley says CN obtained a court injunction that leaves it to police in the southwestern Ontario city to decide whether to end the three-day-old blockade.
Blockade spokesman Ron Plain says the protests are being led by young Aamjiwnaang (AWN'-ja-nong) First Nation members, who met Sunday with representatives from CN, as well as Bradley and Sarnia's police chief.
Dozens of demonstrators set up tables, tents and vehicles on and around the track Friday as part of the national Idle No More protests.
They say the blockade of the commercial-rail corridor will continue until Prime Minister Stephen Harper meets with Attawapiskat Chief Theresa Spence, who is on a hunger strike to bring attention to aboriginal issues.
Bradley says the city doesn't support the blockade, but backs the call by local protesters to speak with Sarnia Conservative MP Patricia Davidson, who did not attend the meeting.
He said protesters and CN continue to discuss the rail stoppage.
"There are discussions going on back and forth," Bradley said.
"We're in the middle trying to be the peacekeepers and ensure that there is no one who is hurt."
CN Rail spokesman Jim Feeny says the rail company is urging governments and police to step up negotiations to come up with a peaceful settlement.
He says the stoppage is starting to affect CN customers, for example it's preventing propane shipments from getting to Canadian consumers.