Cardinal Sean Brady said the Church plans to lobby TDs and Ministers on the issue in the coming weeks.
It comes before an expert group makes a recommendation to the Government next month on how best to legislate for the 'X' case.
Fourteen years ago a Supreme Court judge ruled in the case that a woman should have the right to access an abortion in Ireland if there is a "real and substantial risk to her life".
Cardinal Brady has said the Church believes a new referendum on abortion will have to be held, regardless of the findings of this expert group.
However, spokesperson for Choice Ireland, Sinead Aherne has said it is "inappropriate and irresponsible" of the Cardinal to pre-empt the expert group's recommendations.