President Reagan, promising to push "just as hard as I know how for pro-life measures," moved yesterday to end the use of federal family planning assistance money for abortion counseling and referral.

Reagan also said he has ordered Surgeon General C. Everett Koop to prepare "a comprehensive medical report on the health effects, mental and physical, of abortion on women."

In a speech to antiabortion activists, Reagan said: "We must not rest -- and I pledge to you that I will not rest -- until a human-life amendment becomes a part of our Constitution."

But he acknowledged that the battle will be a long one, and said that in the meantime, alternatives must be found to discourage -- if not abolish -- abortions.

The president said he has ordered the Department of Health and Human Services to draft a proposal to eliminate language in Title X of the Public Health Act that requires recipients of federal funds to list abortion as one option available to pregnant women.

Saying that such language effectively denies Title X grants to antiabortion groups, Reagan said, "I'm directing the secretary of health and human services to publish regulations removing this bias from groups that refuse to take part in abortion activities."

Among the specific changes Reagan suggested were these:Rules governing disbursement of federal family assistance money should "specifically state that a program that does provide counseling and referral for abortion services as a method of family planning will not be eligible." Regulations covering Title X grants would be revised so that "any organization that provides abortion-related services will be required to clearly separate these services" from programs for which federal money is used.

Reagan said under current guidelines, "the coexistence of abortion with federally supported family planning services fosters the view that abortion is an acceptable and government-sanctioned method of family planning."

"In order to insure that this will no longer occur, I'm directing the secretary of health and human services to publish . . . regulations that require grant recipients to separate financially and physically their eligible and noneligible programs." Federal financial support for "activities that advocate abortion" would cease.

Reagan said he has ordered HHS Secretary Otis R. Bowen to propose rules "to ensure that no Title X funds go to any program that encourages, promotes or advocates abortion, or which assists a woman in obtaining an abortion."

Once published, the regulations will take effect after a public-comment period. White House spokesman Marlin Fitzwater said the idea behind the rules changes would be to "protect the integrity of the federal tax dollar" and to show that the federal government does not "endorse, approve or sanction abortion counseling."

Family planning and women's groups attacked the new rules. Patricia Ireland of the National Organization for Women said, "It's a desperation move, it's a lame-duck presidency, it's a discredited administration. We don't believe they're going to be successful."

Faye Wattleton, president of Planned Parenthood Federation of America, and Scott R. Swirling, executive director of the National Family Planning and Reproductive Health Association, said they would file a lawsuit to block the proposed changes.

"We believe this is an outrageous assault on the women of this country and specifically the poor women and the young women of this country whom this program is designed to serve," Wattleton told a news conference.

Reagan, in announcing the study he has ordered from Koop, said the nation needs "a thorough and solid body of public health information on the effects of abortion on women."

Although the president has often spoken out against abortion, the regulatory changes announced yesterday marked the first substantive change the administration has proposed on its own, aside from antiabortion legislation it has had introduced or has supported in Congress.