As Jewish leaders joined the growing apartheid demonstrations, the black woman who helped launch America's civil rights movement when she refused to give up her bus seat, marched with other protesters at the South African Embassy yesterday and said she will not give up her fight "until all are free."

Rosa Parks, now 71, walked the picket line with other supporters of the Free South Africa Movement and spoke briefly and in a frail voice about the civil rights struggle she helped start on a Montgomery, Ala., bus 29 years ago this month.

"I'm grateful to be here today lending my support," said Parks, who recalled the social and economic discrimination she and other blacks experienced during the days of segregation. South Africa's apartheid, she said, is a system "enslaving the black Africans."

Parks did not seek arrest yesterday. But six others -- during two separate demonstrations at the embassy -- did, bringing the arrest total at the embassy to 37 since the protests began Nov. 21.

Nationally, with apartheid demonstrations now being conducted in 12 cities, according to organizers, the arrest total has topped 100; there are plans this week to hold similar demonstrations in four additional cities, including Detroit and Pittsburgh.

At the embassy, a group of Jewish leaders and about 30 marchers pledged their support for the antiapartheid campaign and called on the South African government to end what they called a "gross violation of human rights."

Three members of the American Jewish Congress -- including president Theodore Mann, executive director Henry Siegman and its senior vice president, folksinger and actor Theodore Bikel -- were arrested shortly before 1 p.m. and charged with demonstrating within 500 feet of an embassy, a misdemeanor. They were later released.

Later in the day, shortly after 4:30 p.m., three other persons were arrested for the same offense during what has become a late afternoon ritual at the embassy. The three, Rep. Mickey Leland (D-Tex.); James Farmer, founder of the Congress on Racial Equality, and Bishop Adam DeBaugh, D.C. coordinator of the Metropolitan Community Church, a predominately gay Protestant church, were taken to the 2nd District police station, where they chose to spend the night in the lockup, police said.

In New York, 14 more demonstrators, including Rep. Major R. Owens (D-N.Y.), former Manhattan borough president Percy Sutton and the Rev. William Sloane Coffin, were arrested as protests at the South African consulate there entered a second week.

Since the New York demonstrations began Dec. 3, 42 demonstrators have been taken into custody for blocking the entrance to the building that houses the consulate. Yesterday's demonstration there drew 150 protestors, the largest crowd yet.

During the weekend, apartheid demonstrations spread to Seattle, where 23 persons, including four ministers, were arrested during a protest at the home of an American who serves as South Africa's honorary consul in that city. About 400 people joined that demonstration.

In addition to the American Jewish Congress, the American Jewish Committee and the Union of American Hebrew Congregations announced their support for the protests.

"There are understandable differences over some proposals that have been made to encourage changes in South African policies," Howard I. Friedman, president of the American Jewish Committee, said in a statement. "But there can be no differences among advocates of basic human rights on the need for all people of conscience to speak out on the moral issue involved."

On a day when South African Bishop Desmond Tutu accepted the Nobel Peace Prize, and with President Reagan stepping up his denunciation of apartheid, organizers of the embassy protest were vowing "to go for the long haul" to secure equal rights for blacks in that country.

"We will be here every day, filling the jails of this city and this nation," said Randall Robinson, coordinator of the Free South Africa Movement. He said the embassy and consulate demonstrations will continue, and he warned that the protests may soon be extended to the White House, State Department or firms that trade in Kruggerands, South Africa's gold coins.

Robinson objected vehemently to Reagan's taking credit for the release last week of 11 black trade unionists who had been held in detention since early last month. And, he argued, the president's condemnation of apartheid "means very little unless it's followed by action."

Yesterday's apartheid protest also attracted three counterdemonstrators, who carried signs and distributed leaflets attacking Bishop Tutu as a Marxist.

"He wants to destroy capitalism and bring in socialism," said Carl McIntire, a fundamentalist minister with the International Council of Christian Churches. "Our answer to apartheid is the Christian spirit and time to adjust."