At the Soviet Embassy in downtown Washington, 10 youngsters from around the globe, all clutching bouquets of American Beauty roses, were ushered through carved oaken doors for Coca-Cola and chocolates and a chat about peace with top-ranking Soviet officials. Down the street at the White House, a similar delegation of children bearing flowers and wishes for peace got to talk only to a guard at the gates.

Score one for the Soviets.

When Peace Bird, the West German group that brought the youngsters to Washington for the summit, contacted the embassy, the Soviets apparently knew a good thing when they saw it. But despite calls and letters from the group, the whole affair seemed to catch the White House by surprise. Said one organizer, who went with the children to the gates of 1600 Pennsylvania Ave., "Not a very good civics lesson."

Civics lesson, publicity coup or plea for peace, whatever it was, the children's visit -- coming two days before the summit between President Reagan and Soviet leader Mikhail Gorbachev -- was chronicled by a crush of international correspondents, television camera crews and photographers. Despite the heavy security surrounding the summit, a nun from Georgetown, looking a bit confused, and two peace activist-physicians from Boston slipped into the journalistic crowd and ended up inside the embassy on 16th Street NW.

"What's going on?" said Sister Ann Muriel Ronan, who said she was "just walking by."

The tete-a-tete with the communists was the culmination of the "Bridge to Peace" rally yesterday, organized by a coalition of peace and disarmament groups and attended by hundreds from around the globe to celebrate the arms treaty.

Inside the embassy, the crowd of journalists snapped shutters, dangled huge microphones and knelt by the tiny band of youngsters, somewhat dazed by all the attention, who waited for their meeting seated in damask chairs in the embassy's Red Room. "We will give them cookies, candies, everything," said a Soviet official, gesturing expansively. "Now," he said to the journalists, "you all must go."

The children, ages 9 to 13, from Tokyo, Istanbul, Boulder, Colo., nearby Capitol Heights and other far-flung places, remained to chat with three Soviet officials. They emerged 20 minutes later, and Irene Pingel, a poised 11-year-old from West Germany, pronounced the officials "really nice people," and said the children "asked if we could talk to Reagan and Gorbachev about peace."

"We asked if we could deliver letters, lots of letters. He said he didn't know if Gorbachev can meet with us, but he hopes so."

Yevgeniy Kutovoy, a high-ranking deputy to the ambassador, accompanied the children outside to say the meeting was "excellent," "superb" and "very symbolic."

A videotape made by Soviet photographers "will be immediately shown in the Soviet Union," he said, adding that all the participants had voiced hopes for peace and the intermediate-range nuclear forces treaty to be signed this week.

Over on Pennsylvania Avenue, the children had little to cheer about.

Five-year-old Darren Evans of Pittsburgh, who prefers the nickname Ducky, dragged a red wagon full of roses to a point across from the White House, passed them out to his peace mission colleagues and said they were "going through the guard gate."

It was not to be.

When Latoya Yancey, 11, of Northwest Washington told the guard, "We have to deliver them to President Reagan," he pointed to the Old Executive Office Building next door. "You'll have to deliver them to the mailroom," he said.

The children left their flowers on the ground in front of the guard booth. A U.S. Park Service officer came out later, scooped them up and dumped them in a large green trash barrel.

White House spokesman B.J. Cooper said the Office of Public Liaison received a written request for the children to have refreshments and a chat with either the President or the First Lady, but was unable to fulfill it.

"We regret what happened and we're sorry we weren't there to greet them properly," Cooper said. "We regret the action of the person who picked up the flowers."

The children's visits, East and West, marked the end of the rally yesterday in Lafayette Park organized by SANE/FREEZE, a peace and disarmament group, whose leaders said that members finally had something to celebrate after years on the march.

The last time the group was in Washington for a rally, just six months ago, some members were arrested at the White House in a show of civil disobedience. Yesterday, the story was different.

The peaceful rally began with speeches in the park and ended as hundreds of demonstrators held hands and linked arms, singing "Give Peace a Chance," as they formed a symbolic bridge from the White House gates to a barricade about a block away from the Soviet Embassy.

Earlier in Moscow, in a coordinated event, thousands of Soviet peace supporters formed a similar human bridge, about two miles long, from the U.S. Embassy to the Soviet parliament building as a show of goodwill for the summit. A bouquet of flowers and a message wishing the American and Soviet leaders success at the summit were passed hand to hand along the chain and received by officials at the U.S. Embassy.

For many at the rally in Washington, the signing this week of the INF treaty is a culmination of years of peace movement work to make the climate right for disarmament. Many thought it ironic that the treaty came as it did out of a conservative administration whose tone has been decidedly harsh toward the Soviets.

Margarita Papandreou, wife of the prime minister of Greece and an international liaison for Women for a Meaningful Summit, likened it to the birth of a baby -- "the product of the strangest marriage in contemporary history, the most odd of odd couples: Ronnie and Mikhail."

"The baby will be baptized by the peace movement because we, after all, arranged the marriage. It was our long and diligent efforts that accomplished it."

The peace movement's celebration marked the beginning of nearly a week of nonstop rallies by those trying to send a message to the Soviet general secretary. Many of those messages will be negative, from ethnic groups and national movements angered by what they believe is authoritarian Soviet policy.

Yesterday, a small show of protest by the Social Democrats, USA, who are holding a convention at the Madison Hotel, was thwarted when the hotel management demanded that the group take down a sign proclaiming "Free Soviet Jewry." The hotel manager, according to a group member, told the organization that the sign might offend the Soviet delegation staying at the hotel.

Rita Freedman, the organization's executive director, later commented, "Apparently the Soviets haven't told the hotel staff about glasnost."

The sign at the Madison carried the same message that Jews hope to take to the world in a protest today. It will start at about noon on the Ellipse and continue with a march to the Mall, where the crowd will hear speeches from politicians, activists and former refuseniks, including Natan Shcharansky, perhaps the Soviet emigration movement's biggest hero.

Yesterday, a far smaller group with the same plea held a prayer vigil for refuseniks on K Street NW outside the offices of Aeroflot, the Soviet national airline. One woman in the group, Shirley Goldstein of Omaha, wore a black sweatshirt that read: "Glasnost -- Shmasnost! Summit -- Shmummit! Just Let Our People Go!"

After dark, the group held another vigil, this time by candlelight, across from the Soviet Embassy. Rabbi Avi Weiss, who heads the Center for Russian Jewry, said, "The candle was lit to let the Soviet government know that Jews will protest until at least 50,000 refuseniks are allowed to leave the Soviet Union annually."

Earlier, Weiss had walked by the Soviet Embassy just after the children went inside. He said he recognized "the ability of children, in their innocence, to express a yearning for peace." But he added that real peace "also means freedom . . . opening up the gates" of the Soviet Union to let Jewish people out.

The children themselves, sounding older than their years, spoke during interviews of the uncertainties in the summit they had come to witness.

Belgi Tarakcioglu, 11, of Istanbul said the summit would be full of promise, "if Reagan and Gorbachev are sensible."

Irmina Szczesniak, a ninth grader from Poland with a head full of blond curls, sounded less optimistic. "I don't know if either of them is doing anything," she said. "I think they are just pretending. It is just a game. Neither . . . wants to say the other is right."

Some of the children struggled with the English language and others translated for them, but certain things they knew by heart: that politicians should listen to children. That 230,000 letters collected by Peace Bird show that children "have ideas of peace." That they fear nuclear weapons.

After their meeting at the Soviet Embassy, they acted, well, just like children.

"It was nice to be in the spotlight," said Mashadi Matabane, a pig-tailed 10-year-old from Capitol Heights. She couldn't wait to tell her friends in school. "Are they ever going to be mad."

Staff writers Lynn Duke, David Hilzenrath and Carlos Sanchez contributed to this report.