About 25,000 abortion foes, bearing red roses to symbolize the unborn child, marched through Washington yesterday calling for an end to legalized abortion, while abortion advocates announced the start of a $3 million campaign to fight antiabortion legislation.

The ninth annual "March for Life" began with a meeting among antiabortion leaders and President Reagan at the White House and ended with the marchers descending on Capitol Hill to urge their congressmen to support what they call "prolife" legislation.

The protest marks the anniversary of the 1973 Supreme Court decision legalizing abortions. According to police estimates, the march attracted about half the number of participants as last year.

Though Reagan declined to meet with abortion advocates and reiterated his opposition to abortion, many marchers nonetheless expressed their disappointment that the president has not pushed harder for passage of any of the more than two dozen antiabortion bills pending in Congress.

"It's a perfidious stab in the back," Bill Moffatt, a public relations man who flew in for the march from Eagle River, Alaska, said of Reagan's stand.

The president sent a message to the crowd through Health and Human Services Secretary Richard Schweiker saying that he is looking forward to one of the antiabortion measures "reaching my desk for action." But when Reagan met with leaders of the movement, he gave "no commitment" that he would endorse any specific legislation in Congress, according to March for Life organizer Nellie Gray.

"The words were beautiful," Gray said after her meeting with Reagan, "but the words have to be backed up with action. One year is long enough to put prolife legislation on the back burner."

As Gray spoke to the crowd on the snow-covered Ellipse, many of whom had spent the night on buses traveling to the march from Maine, Ohio and Missouri and Kentucky, the Religious Coalition for Abortion Rights was holding a service inside the New York Avenue Presbyterian Church. Its message: the right to choose abortion is a matter of religious freedom.

The service was disrupted several times by abortion foes.

"Sacrilege . . . . This is an abomination!" shouted three men who tried to stop the service. A brief scuffle ensued between the men and some women attending the service.

Addressing moves afoot in Congress to protect the rights of the unborn, Bishop J. Brooke Mosley of the Episcopal diocese of Pennsylvania told the group of about 250 persons at the service, "To try and settle this age-old question by a majority vote of 20th century congressmen is absurd. When a person becomes a person is a matter of belief.

"No government has the right to force a particular belief on us," he said.

Speeches on the Ellipse, however, declared quite the opposite. Gray, in the keynote address, urged abortion foes to rally behind a recent proposal known as the "paramount life" constitutional amendment, which guarantees the right to life of the unborn child and prohibits abortion under virtually all circumstances. The measure was introduced in the House last December by Rep. Thomas A. Luken (D-Ohio) and Rep. Robert K. Dornan (R-Calif.).

Sen. Jesse Helms (R-N.C.), sponsor of several antiabortion measures, also called on the marchers to unify behind a specific bill rather than arguing among themselves over how tough controls on abortion should be.

Reagan, Helms said, "did impress on me that unity is essential."

Currently, the antiabortion movement appears split between those who support a proposal by Sen. Orrin G. Hatch (R-Utah) to give individual states the power to restrict abortions, and those who want to ban abortions except where the life of the mother is endangered. Gray said the March for Life organization and the National Right to Life committee both support the "paramount life" amendment, while the National Conference of Catholic Bishops has endorsed the Hatch proposal.

In a press conference in the Russell House Office Building yesterday, the national Abortion Rights Action League announced plans to raise $3 million to help elect what it calls "prochoice" candidates to Congress and state legislatures. Part of the money will also go to pay for print, radio and television advertisements urging voters to express their opposition to the antiabortion measures before Congress.

One of the ads, created by the McLean firm of Bailey, Deardourff & Associates, features a white-robed physician who declares, "No woman should be forced to remain pregnant against her will. But unless you act immediately . . . the U.S. Senate will take a major step to make abortion a crime and deny women the right to make their own choice."

Alleging that the "right to life" movement is "in disarray," the league's executive director, Judith Widdecombe, asserted that recent polls show most Americans believe abortion should be a matter of choice. Membership in the league grew by 50 percent last year, she said.

But marchers yesterday declared that their movement is stronger than ever.

"I don't feel like we're out of step with the times," said Alaska Right to Life member Dorothy Bassett, mother of five and grandmother of nine. "I think this country has just gone through a 20-year period when it was out of step." Behind her a child carried a picture of a baby with the caption "Thank You Mom," and several protesters wore signs that read, "How Would You Have Liked To Have Been Aborted?"

There was heavy representation from Catholic groups such as the Knights of Columbus and fundamentalist Christian groups. But there were also many in the crowd, bundled up against the cold in bulky coats, scarves and mittens, who said they came not for religious reasons but because they simply think abortion is wrong.

"I've noticed a lot of people my age . . . . are almost embarrassed to say they are against abortion," said Janet Lawler, 21, a freelance writer from Dutchess County, N.Y. "It's drummed into them that you're not liberated if you're not for abortion."

Lawler, who came with 46 others by bus, is Catholic. But what "convinced" her abortion is wrong, she said, was not her church's stand, but a course she took in prenatal care in which she learned about how an unborn fetus reacts even to sounds its mother makes.

Ken and Irene Hughes of Fort Worth, Tex., whose child was born with brain damage and cerebral palsy, said they wholeheartedly disagree with abortions in cases where the fetus is likely to be born with a serious illness.

Washington Post staff writer Ed Bruske contributed to this article.