Ireland's strongly nationalist prime minister, Charles Haughey, has asked Irish Americans to shun militant Irish nationalist groups in the United States who support or condone terrorism by the Provisional Irish Republican Army in British-ruled Northern Ireland.

While reiterating his policy if striving for the peaceful unification of majority-Protestant Northern Ireland with predominantly Catholic Ireland, Haughey yesterday condemned more strongly than ever before the "campaign of violence" by IRA terrorists in Ulster and the crime wave they have caused in Ireland itself by robbing banks to finance attack's on British and Ulster Protestant security forces in Northern Ireland.

Haughey (pronuonced HAW-hee) said IRA terrorists and their "misguided" supporters in some militant Irish American groups were harming rather than advancing the cause of Irish unity. He promised to intensify security measures against terrorists who use Ireland as their base for assasinations and bombing across the border.

The Irish prime minister, who has made Irish unity the top priority of his eight-month-old government, had been under strong political pressure from the IRA and Irish American groups who support it after two Irish policemen were killed earlier this month in a bank robbery attributed to terrorists. Haughey also had been criticized by opposition political leaders for intending, before being forced to change his mind, to replace Ireland's ambassador to Washington, Sean Donlon, an outspoken opponent of Irish-American groups who sympathize with the IRA

In a major speech on IRA terrorism to members of his nationalist Fianna Fail Party yesterday in Cork, Haughey gave in to demands by opposition political leaders that he specifically disown two Irish American groups that Donlon opposes: the New York-based find-raising organization, the Irish Northern Aid Committee (Noraid) and the Washington-based lobby, the Irish National Caucus.

Noraid has solicited money from Irish American for the IRA, and the caucus has blamed Britain rather than the IRA for the violence in Northern Ireland.

Haughey acknowledged that "there is clear and conclusive evidence available to the government here from security and other sources that Noraid has provided support for the campaign of violence and indeed direct assistance in its pursuit."

He said Noraid "stands condemned and I appeal to all in America who have the interests of Ireland at heart not to give this body any support, financial or moral."

The Irish National Caucus also has "undesirable associations" with Noraid, according to Haughey. "The evidence available to us of the associations that exist between Noraid and the Irish National Caucus," he said, "casts grave suspicion" on the caucus, which has disavowed any connection with the IRA although it has brought IRA representatives and other militant Irish nationalists to Washington.

No Irish American, Haughey said, "whether private citizen or elected member of Congress should be any statements or association, lend support to those whose actions serve only to delay Irish unity."

This appeared t be a veiled reference to the Ad Hoc Congressional Committee on Irish Affairs chaired by Rep. Marlo Biaggi, which the Irish National caucus claims to influence. Giggi's name was missing from a list of American politicians who Haughey said supported his policies of combating IRA terrorism while also pressing for Britain to agree to negotiation leading to Irish unification.

Haughey added that he recently received message of support from these politicians -- Sens. Edward Moynihan, (D-N.Y.) House Speaker Thomas P. O'Neill (D-Mass.) and New York Democratic Gov. Hugh Carey -- after they interceded to stop him from replacing Donlon, with whom they had worked closely in opposition to Biaggi and the Irish National Caucus.

Hanghey, however made clear his belief that Irish Americans could be persuaded not to aid terrorists they believed were fighting for Irish unity only if his policy of seeking the same goal through peaceful means showed some progress. He repeated that peace was possible only if Britain agreed to negotiations on Irish unity with Ireland and political leaders in Northern Ireland.

Instead, the British government of Prime Minister Margaret Thatcher is trying once again to win agreement from Ulster politicians on a home-rule government in which the Protestant majority and Catholic minority would share power under British rule.