Luas boss Gerry Madden has warned there is no contingency plan in place for its 90,000 customers if drivers go on strike.
The Transdev Managing Director also urged drivers to call off two 48-hour work stoppages next month, as there was no resolution in sight to end the dispute.
He said Siptu's claim for pay rises up to 54pc is "unrealistic" and must reflect "pay developments in the economy in general".
Mr Madden said drivers should not expect the same pay as Irish Rail employees, as their roles are more comparable with bus drivers.
Siptu has lodged claims ranging from 8.5pc to 53.8pc.
It has refused to defer strikes - on Thursday and Friday, February 11 and 12, and the same days the following week - despite agreeing to talks last week at the Workplace Relations Commission.
The commission is currently considering whether there is any point in hosting more talks.
"Regarding contingency plans, an alternative service at this point in time to the Luas is doubtful if there is a 48-hour stoppage," said Mr Madden, in response to questions from the Herald.
"A total of 90,000 people travel on Luas daily and the safety and comfort of their commute must be taken into account."
He said Transdev is working on contingency plans and "should they materialise" the company will inform customers as soon as possible.
Some drivers on €42,247 a year are seeking pay rises of up to 54pc, to €64,993, more than an Irish Rail driver.
Mr Madden said tram drivers are better compared with bus drivers, not train drivers, and this was a "transport industry standard".
"Luas is a light rail operation, Irish Rail operates heavy rail," he said. He added that the training period for a Luas driver is seven weeks and they do not require rail industry experience.
In contrast, Irish Rail drivers need rail experience before they are recruited and spend up to three months in a classroom before undertaking further training for 12 months.
In addition, Irish Rail has multiple routes and multiple depots, and a more complex network with different train types.
Mr Madden said Luas drivers work on average 36 hours per week, while Irish Rail drivers work on average 43 hours per week.
"Call the strike off and come back to the table," he urged staff.
"Make sure to talk to your local union representatives and ask them about their strategy given the unrealistic nature of the claims."
He said Siptu must revise its significant pay claim in order for meaningful talks to take place.
"We are willing to discuss, but in a context. Siptu must take into account general pay developments within the economy and the company's financial position."