The Luas operators have appealed for trade union bosses to call off Friday's strike and focus on negotiations on a pay deal.
Transdev boss Gerry Madden made the public plea to Siptu but warned tram drivers that his company was not going to better a salary increase already given to ticket inspectors and other staff.
In what has become a deeply bitter and long-running dispute, drivers are facing the prospect of being docked a day's pay for any four-hour stoppages they hold in June.
Mr Madden said: "We understand the frustration of the public who, like us, wish to see this dispute resolved and we appreciate their ongoing understanding as we seek to achieve a fair resolution.
"The company is not prepared to conclude an agreement with the drivers that provides for increases in excess of what has been agreed with the other grades up to September 2019."
Friday's Luas shutdown is the latest of five 24-hour stoppages in the diary with another planned for May 27.
Every day the trams do not run, about 90,000 people must find other transport around Dublin while Transdev claims it loses hundreds of thousands of euro.
A separate four-hour stoppage is also planned for May 26 and others will affect the Luas in June while Leaving Certificate exams are on.
Transdev said further strikes will force it to consider "other lawful means" to end the dispute but warned that managers were not prepared to put the tram service at further risk during the state exams.
Three other grades of staff in Luas accepted a new pay deal after weeks of talks and industrial action.
They will reportedly get wage increases of around 13% up to September 2019, taking their salaries to around €51,000 at the top end and before a bonus and overtime is paid. New entrants will be paid less.
Transdev said it would a "very fair package of remuneration for tram drivers".
The company said it does not want to prolong the dispute and is open to talks immediately.
Transdev also claimed all its responses in the row are lawful and follow the strike action, which it said is eating into resources available to resolve the dispute.