Heads turned and a murmur of appreciation spread through the celebrity-studded crowd full of tuxedos and sequined gowns. Through a side door, a diminutive black man clothed in the fuchsia robes of the Anglican Church had slipped into the ballroom of the Waldorf-Astoria.

As he walked to the ballroom's platform, hundreds of guests rose in a standing ovation. Jacqueline Onassis, Sen. Edward M. Kennedy (D-Mass.) and Atlanta Mayor Andrew Young joined chief executive officers of major U.S. corporations and Wall Street lawyers in applauding Desmond Tutu, 53, a descendant of Zulu and Xhosa tribesmen, bishop of Johannesburg, South Africa, and now, winner of the Nobel Peace Prize.

If the war against apartheid is being waged in the dusty streets of South Africa's black ghetto "homelands," it is also being fought in 1960s-style protests outside the South African Embassy in Washington and from as many U.S. pulpits and forums as Tutu, one of South Africa's best-known black leaders, can claim.

Tutu, who has been on sabbatical in New York this fall, has become a powerful voice for the growing anti-apartheid movement here as he has criticized the Reagan administration's policy of "constructive engagement," diplomacy that avoids outspoken criticism of South Africa.

"Where is the anger?" he demanded, leaning across the podium at Tuesday night's Waldorf-Astoria benefit for the African-American Institute, a private group promoting U.S.-African cooperation. "Constructive engagement has given a bad name to democracy. Constructive engagement is an abomination, an unmitigated disaster."

For the United States to "collaborate with apartheid," he said, is tantamount to condoning the internal policies of Nazi Germany or the Soviet Union under Joseph Stalin.

Tutu's Nobel Prize and his crusade in the United States coincide with a period of violent unrest in South Africa that has followed the adoption of a new constitution that gives partial political representation to mixed-race "coloreds" and Asians of Indian descent but not to the country's 24 million blacks, 73 percent of the population.

Tutu and another South African religious leader, Allan Boesak of the World Alliance of Reformed Churches, have persuaded Kennedy to visit South Africa in January.

In a speech during the Institute benefit, Kennedy warned that U.S. corporations investing in South Africa "must actively work to end apartheid, not just live with it." Under the so-called Sullivan principles, set out by the Rev. Leon Sullivan when he was a board member of General Motors Corp., U.S. corporations investing in South Africa agree to improve black workers' wages, training and housing as well as to provide racially integrated work places.

Tutu's speeches breathe rage. But his puckish wit and gentle manner also have helped captivate American audiences. Admirers ask for his autograph. More than 1,000 people showed up at a neighborhood party for him in Chelsea, a middle-income neighborhood in Manhattan.

"A hero," Paul Moore, the Episcopal bishop of New York, said of Tutu. "But a disarming kind of hero." Moore and Jesse L. Jackson joined Tutu at an ecumenical service for more than 700 at the Cathedral of St. John the Divine here.

Tutu began his address with a joke. "When the missionaries first came to Africa," he said in his lilting African-British accent, "they had the Bible and we had the land. They said: 'Let us pray.' We closed our eyes. When we opened them, the tables had been turned: We had the Bible and they had the land." The crowd roared.

Tutu said his heart has been warmed by his U.S. reception. "A man writes to me from the woods in California. He says 'I am praying for you.' " Raising his hands to the sky, the bishop says, "Praying for me in the woods of California? Can you believe it? What chance does the South African government have when a man prays in the woods in California that it will change?"

At midnight, after the Waldorf speech and after moving through the crowd like a politician at a wedding, patting backs, cracking jokes, hugging old friends, Tutu gives interviews. "He's a bubbling fountain of joy amidst the turmoil of South Africa," Andrew Young said.

Being interviewed, Tutu crosses his legs casually and laughs easily, despite having had his passport confiscated, having spent nights in jail, having marched in illegal protests, having alleged that his phones are tapped and his office bugged by the South African police.

Tutu warns of a "blood bath" that may occur if apartheid is not eradicated. The Nobel Prize, he said, "makes a very important political statement. It comes after the same prize was given to Lech Walesa. It recognizes that those who oppose apartheid are like those who oppose communism. The prize says that we are the agents of peaceful change."

Moreover, he adds, the prize "has given hope to some of us who felt that evil was on the rampage. Now we have a wonderful signal by God that right will prevail."