SIPTU say they are "dismayed" at the failure of Transdev's CEO to meet with Luas workers while he was in Dublin this week.
In a statement this evening SIPTU Sector Organiser, Willie Noone, said: "It is deeply disappointing and inexplicable that Mr Stevens would visit Dublin and not meet with Luas workers."
The CEO of the company which runs the Luas service in Dublin has written to all staff, asking them to engage "constructively" with management.
In a statement issued ahead of another 48-hour strike this weekend, chief executive of Transdev UK and Ireland Nigel Stevens also said the current demands of staff went "way beyond current norms in the private and public sectors".
Two further days of strikes are planned for later in April.
He said the pay demands were "totally unaffordable" and there was no money for further hikes to pay, over what was agreed when the sides met at the Workplace Commission.
However, he said the company was prepared to conclude a "fair and balanced agreement" in line with pay norms in other sectors.
Mr Stevens said he was deeply disappointed at the current situation, and that the company was in particular "acutely concerned for all their customers who have been impacted by this dispute".
Staff rejected proposals from the Workplace Commission last week for increases of up to 18% over three years.