The Social Protection Minister Regina Doherty says there is no guarantee that a pension problem affecting some 40,000 people will be fixed before the next budget.
Changes made in 2012 mean women in particular, who took time out of work to raise families, lose out on around €35 a week.
Protestors are highlighting the issue outside Leinster House on Thursday afternoon.
Groups representing older people, women and workers have urge the minister and the Cabinet to reverse the changes and to work towards a fair State pension.
Sinn Féin deputy Leader Mary Lou McDonald has also called on the Government to reverse the "discriminatory" changes.
Speaking in the Dáil, she said: "This discrimination disproportionately affects women who exited the workforce to raise children and look after families, and who then returned to employment later in life to qualify for the maximum payment. These changes hurt some men too.
A protester holds a placard outside Leinster House | Image: Paul Quinn
"The Fine Gael-led Government of the day made these changes in the full knowledge of the weekly cut to payments and that the change would disproportionately impact women."
"The Minister for Social Protection has acknowledged that these citizens have been wronged and whilst she has vowed to fix it she has expressed the view that something magical will have to happen to find the money."
While Minister Doherty says she is doing her best to fix it.
"Well the only assurance I can give is that we've done extensive work to address and to report on the issue, and I have a proposal going to Cabinet.
"The outcome of that meeting obviously is - I obviously would be ambitious and hopeful - but I can't determine the outcome of that meeting.
"So the only reassurance that I can give those people is that I'm going to fight very, very hard to make sure that we address the anomaly as I have said on numerous occasions".
Reporting by Paul Quinn and Jack Quann