Sinn Féin's Martin McGuiness was responding to criticism from the leader of Catholics in Ireland, Archbishop Eamon Martin.
He had said anyone who supported abortion in any circumstances was not "in communion with the church".
But speaking to the BBC Mr McGuiness said it was not incompatible with Catholicism to support some terminations.
Northern Ireland is currently considering a bill that would allow abortion when it was likely a baby would be born dead, die soon after birth or if the pregnancy was a result of rape.
"I try to be the best Catholic I can be," Mr McGuinness said adding that the "Catholic Church is made up of people who have different opinions on different issues."
But he told the BBC's Inside Politics on Friday Sinn Féin's opposition to on-demand abortion was still strong.
He said he had been moved after meeting a Northern Irish woman who had to travel to England for a termination because her baby had no chance of survival.
"I think, in the context of my responsibility as a government minister and other government ministers who have a duty to pass legislation, when we're faced with the case of Sarah Ewart, we have to deal with that in the most compassionate way possible."
He said people who claim a change in the law would cause woman to choose abortion more easily were wrong: "I totally and absolutely contradict those people. I think what we need to do is recognise our responsibilities to support women when they make the choice.
"This is not about women being forced to do anything, they should be able to make their own choice. I absolutely respect the right of people to do that."
The Catholic Church says it remains opposed to any change to the existing laws.