A retired marine and veteran of many civil rights marches, Jake Wells of Southeast Washington forsook the lure of the tennis court yesterday to join a picket line in front of the South African Embassy on Massachuetts Avenue NW.

"Anytime someone is mistreated, I'll provide the presence," Wells, 75, a tall, balding man said of his decision to join an estimated 900 demonstrators who were protesting the South African government's recent repressive measures against blacks, including the arrest of antiapartheid leader Bishop Desmond Tutu.

Among those protesting the apartheid system of racial segregation in South Africa were national politicians, labor and religious leaders, social activists as well as professionals and business people.

Amid the chants of "Freedom Now, Apartheid No," the demonstration ended with the arrest of 64 people who, after stepping off a brown bus, walked across the grounds of the South African Embassy and tried to ring the doorbell.

They were quickly whisked away by police officers and charged with a misdemeanor of demonstrating within 500 feet of an embassy. The demonstrators, including Del. Walter E. Fauntroy (D-D.C.), Rep. John Lewis (D-Ga.) and Mary Berry of the U.S. Civil Rights Commission, were later released on personal recognizance, police said.

The maximum penalty for the misdemeanor offense is a $100 fine and 60 days in jail.

Organized by TransAfrica, a national organization that lobbies on behalf of issues affecting Africa and the Caribbean, the demonstration was called in response to South Africa's decision last week to ban 17 antiapartheid organizations from conducting political activities, followed by the arrest of Tutu, who has since been released, and several other apartheid foes.

Another impetus for the picketing is pending legislation in the House and the Senate to impose more comprehensive sanctions against South Africa because of its continuing repression of the black majority by the white South African government, said Ibrahim Gassama, a legislative assistant for TransAfrica.

The economic sanctions bill is scheduled to be taken up by the House subcommittee on Africa later this month, officials said.

A short speech by Molly Yard, president of the National Organization for Women, drew hearty applause and captured the spirit of the day. "If I were a minister, I'd pray for the soul of {South African President Pieter W.} Botha," she said, "I'd pray, 'Father, forgive them for they know not what they do.' What they don't know is that they are the architects of the path to their own oblivion."

After the march, Victoria Carter, 25, of Adelphi prepared to wheel twins Garret and Glorietta Thomas, who are 1 1/2 years old, back to her car for the trip home.

Carter explained that she babysits with the twins before she goes to her afternoon job as a security guard. She had heard about the march on the radio the night before and had decided she wouldn't miss it even if it meant bringing the children.

"We wanted to show we are all in solidarity with the women of South Africa," said Carter.