Aer Lingus is to axe 100 jobs by the end of the year.
The carrier said it is introducing a voluntary severance scheme, despite an increase in business.
Christoph Mueller, Aer Lingus chief executive, said the cost-cutting plan was being brought in to protect profits.
"In line with the ongoing requirement to streamline our organisation structure and identify cost saving initiatives, we are launching a voluntary severance programme, with a goal of reducing headcount by approximately 100 staff by year end," he said.
While long-haul passengers were up more than 14% during the first three months of the year, the airline has been hit with higher fuel and airport charges, it said.
The carrier is also getting fewer passengers on its UK routes.
However, business was up overall, bringing in 259.7 million euro at the start of the year, up more than 3% on the same period last year.
Overall passenger numbers have also increased by more than 2% while the money the carrier is making from fares has risen by more than 6%.
Despite this, Aer Lingus said it was loss-making at the beginning of this year, largely down to start-up costs for a new lease operation to Virgin Airways in the UK.
It is also affected by planned changes to the long-haul fleet and the weaker business on UK routes.