"As a responsible Government, you don't just go around hollering 'genocide,' " David Rawson, the United States Ambassador to Rwanda, said in an interview. "You say that acts of genocide may have occurred and they need to be investigated." Cries of Hypocrisy

Diplomacy is not famous for haste or blunt truths, and American Administrations have proven slow in denouncing slaughter in Central Africa, including the tribal massacres in Burundi last fall. It was only this month that the State Department agreed to establish an office to look into what the Administration now portrays as five years of genocide under Pol Pot in Cambodia that ended 15 years ago.

But with Rwanda a gruesome feature of international news coverage since early April, those troubled by international passivity have begun to lash out with particular venom at what they describe as the Administration's hypocrisy.

Herman Cohen, a former Assistant Secretary of State for Africa, used an op-ed article in The Washington Post last week to lambaste the Clinton Administration for what he called its "wimpish approach" in Rwanda. Mr. Cohen declared flatly that the killings there "must be called genocide."

"Another Holocaust may just have slipped by, hardly noticed," Mr. Cohen wrote.

Geraldine Ferraro, who headed a United States delegation to a special session convened by the United Nations Commission on Human Rights, used the less than categorical language on May 25 to outline the American position. A day later, the State Department described the question of whether genocide was being committed in Rwanda as one that is "under very active consideration."

But Mr. Rawson said this week the Administration intended to await a United Nations report which is not scheduled for four weeks. Political as Well as Ethnic

Because the bloodshed has been rooted in political as well as ethnic tensions, sorting out the killings could prove complicated. Witnesses have said Tutsis were the victims of the worst violence, much of it carried out systematically by Government troops and Hutu militias, but Hutus have been killed in reprisal and in battles with the Rwandan Patriotic Front, the Tutsi-led rebel group that now controls half of Rwanda.