The Financial Services Union (FSU), which represents workers in the tech sector, has described the tone and messaging of the announcement of layoffs at META as "disrespectful" and something that should not be tolerated.
Meta has not said how many layoffs there will be at the company's Irish operation which employs around 2,000 people.
The Department of Enterprise said it has not received a collective redundancy notification from Meta.
Job cuts of thirty or more would require such a notification.
In January, Meta said it would cut around 5% of its "lowest performing" staff globally.
The company said that the workers that are made redundant will be replaced by new hires meaning there will be no overall reduction in headcount.
"The comments from the CEO of META that he would move out 'low performers' is disrespectful to hard working staff and certainly goes against the spirit if not the redundancy law in this country," said the union's Head of Industrial Relations and Campaigns Gareth Murphy.
The union said it will open a confidential freephone helpline for workers in Meta tomorrow.
A company spokesperson said today that any jobs that are cut will be backfilled.
"We have the highest confidence in the fairness and robustness of our performance review process and impacted employees are being provided with generous severance packages," Meta said.
