The provincial government is set to bring in legislation that includes a 90-day cooling off period as early as Monday. Port Metro Vancouver has also announced both unionized and non-unionized truckers whose licences and permits are about to expire won't have them extended if they don't return to their jobs.
Only unions can be legislated back to work, but Unifor members say they will not cave under pressure.
"These workers will not be cowed, we will not be bullied, we will not be swayed," Unifor spokesman Gavin McGarrigle told the crowd Friday.
"We need to get around the negotiating table, sit down and get this thing done in a way that there's a standard rate for everyone across the board."
McGarrigle said it is too early to predict what unionized truckers will do once the back-to-work law is in place, but he expects the cooling off period will further anger workers.
More than 1,000 non-union truckers have been on strike since late last month, and several hundred Unifor members joined the job action March 10, demanding shorter wait times at the port and standardized rates of pay across the sector to prevent undercutting.
Port Metro Vancouver's vice-president of operations, Peter Xotta, has said the labour dispute has had a significant impact on operations and the port's reputation.
Xotta said earlier this week that truckers who are not prepared to return to work immediately won't have their licences renewed.
Harman Shergill, who speaks for the United Truckers' Association of B.C., which represents non-unionized workers, said the licence terminations mean little to operators who no longer have funds to put into their vehicles.
"On one side they are telling us our concerns are legitimate, but if it's legitimate, why are they overlooking them?" he said. "Let's sit on the table and negotiate."
A government-backed 14-point proposal was introduced last week to persuade the truckers to return to work. The plan includes a 10 per cent rate increase within 30 days and compensation for wait times, but the truckers rejected it, saying it wasn't enough.
A spokesman for Port Metro Vancouver accused the truckers on Friday of holding the port hostage.
"People are losing their jobs and businesses may go under because truckers insist on negotiations where negotiation is simply not possible," said a statement released by port spokesman John Parker-Jervis.
The truckers are not employed directly by Port Metro Vancouver. They are usually independent contractors or sub-contractors working directly for shipping companies.
Unifor's national president Jerry Dias, members of several other labour unions and New Democrat politicians, including B.C. NDP leader Adrian Dix, attended the rally in support.
Dix said he doesn't expect the back-to-work legislation to pass by Monday.
"What's got to happen here is people have got to come to the bargaining table and bargain in good faith, and the provincial government's actions make that harder, not easier," he said.
The strike has affected the port's four container terminals in Metro Vancouver. At its peak, the job action was estimated to be costing the Canadian economy about $885 million. However, the port said container truck traffic is now up to 40 per cent of normal.
Follow @vivluk on Twitter