In a demonstration reminiscent of the antiwar protests during the Vietnam era, an estimated 23,000 people marched through Washington yesterday on the eve of elections in El Salvador to protest U.S. policy in that country.

"No draft, no war; U.S. out of El Salvador," the marchers chanted as they walked from Meridian Hill Park on 16th St. NW through the largely Hispanic community of Adams-Morgan to Lafayette Park across from the White House. "The rebels want to talk. Let's listen," read one banner.

The demonstrators, many of whom came on buses from other cities, were protesting the U.S. government's military and economic aid for the civilian-military junta in El Salvador that is locked in a war against leftist insurgents.

Under a bright blue sky, and against nose-numbing winds that snapped the flags and banners carried by some marchers, the demonstration began with a morning rally in Meridian Hill Park.

There, dozens of speakers, including a representative of the Salvadoran Democratic Revolutionary Front, which opposes the elections, criticized U.S. involvement in the conflict.

The march, which culminated with another rally at Lafayette Park, was organized by the March 27 Coalition, a grouping of 16 activist organizations that oppose the adminstration's Salvadoran policy.

Participants in the demonstration represented a variety of political groups, but their common concern was that the administration's involvement in El Salvador would escalate to match the U.S. involvement in Vietnam and that the money being spent for weapons would be better spent for social services, both here and in El Salvador.

"I feel we have no business interfering in the affairs of El Salvador," said hospital attendant Mark Zucker, who came from Detroit for the march. "They're trying to gain their freedom so there won't be the kind of poverty and exploitation that exists now. If they want to have a revolution, it's their right to have one."

"We had ours," added Robert Sinclair-Smith, also of Detroit.

A Maryknoll nun from Baltimore, Helen Scheel, said that she had come to the march because she "would like the people of El Salvador to be able to determine their own future. I feel very ashamed about our government."

Four religious workers, two of them Maryknoll nuns, were slain in December 1980 by government troops in El Salvador.

Jenny Cali, a medical receptionist from Silver Spring, watched the march warily as it proceeded down Connecticut Ave. She said that she does not "believe in protests." But when asked if she had strong views on El Salvador, she replied: "Yes, I don't want us to get involved in it. I have four sons and I don't want them to go there."

Few Salvadorans participated in the demonstration and, in contrast to the Americans who were involved or who watched from the sidelines, most Salvadorans questioned in a spot survey along the route of the march were noncommittal about the demonstration.

Antonio Velasquez, who said that he had come here from El Salvador a year ago, stood on a curb in Adams-Morgan watching the march pass by. Asked what he thought of the demonstration, the 46-year-old restaurant worker replied: "I cannot say yes or no, because politics is something I just don't understand. It doesn't make any difference to me. We want to end up a free country, but not like Cuba."

Jose Canas, 20, said he has been in the United States for two years. Yesterday he leaned against the hood of a car and silently watched the demonstration. He said that he supports what the marchers were saying, and added: "If it were taking place in El Salvador, it would be even better."

The demonstration was the largest in Washington protesting U.S. involvement in the El Salvador conflict since a march on the Pentagon last May that drew almost 25,000 people.

Yesterday's marchers included representatives of labor, religious, antidraft, antiwar, homosexual, Indian, black and Hispanic rights groups. Even a group called "The New Jersey Tenants Association" was there, demanding "homes, not condominiums."

The protest drew a crowd of onlookers, including at least one member of Congress, Rep. George Miller (D-Calif.).

Organizers of the demonstration claimed that 50,000 protestors participated in the march and rally, but D.C. Police and U.S. Park Police estimated the crowd at 23,000.

Among the speakers at the rally was Detroit City Council member Mary Anne Mahaffey, who presented Arnoldo Ramos, representative of the Salvadoran Democratic Revolutionary Front, with the key to the city of Detroit. The council recently voted unanimously to give Ramos the honor and to endorse the march.

The demonstration gave some spectators a feeling of deja vu.

"It's sort of throwing me back in time, I'm getting flashbacks," said a 39-year-old chemist with the Environmental Protection Agency who did not want to give his name. He had come downtown to see the march that was like many he had participated in years ago to protest the Vietnam war. "It all looks suspiciously similar," he said.

A separate rally by a leftist group called the Anti-Imperialist Coalition, which advocates outright military victory for the insurgents, also was held yesterday. About 500 people assembled in Meridian Hill Park and marched to Farragut Square for their rally. Police maintained a barrier around the group because of friction between its leaders and those of the March 27 Coalition.