The message Nelson Mandela brings to the United States is different from that of Eastern European leaders who also have come here this year for celebrations of their struggles for freedom.

Instead of wooing American investment, Mandela, at least for now, wants to discourage it. Instead of debunking socialism, Mandela is embracing it as one possible way of undoing the injustices of apartheid, South Africa's system of racial segregation.

Throughout his recent tour of Europe and Canada, Mandela stressed the need to maintain economic pressure on the South African government during talks about the country's future. He has insisted that it would be premature to invest in South Africa or lift trade sanctions.

Mandela is expected to repeat that message in New York Friday when he meets with more than 100 U.S. business leaders, many of whom represent companies that have been involved in South Africa or could be major future investors. The group will include officials of Citibank, Manufacturers Hanover, Coca-Cola, Colgate-Palmolive, American Express, Bear Stearns, and Leon Templesman & Sons, a diamond concern.

"I think he'll be saying this is a new era and a new time, but things haven't changed yet," said Richard Knight of the American Committee on Africa.

The United States, South Africa's biggest trading partner until the mid-1980s, is an especially important place for Mandela to make this point. At least 120 U.S. companies still have direct investments in South Africa, although that figure is down from 350, and more than 200 others have licensing and franchise agreements with firms there.

With prospects apparently somewhat improved for an eventual negotiated settlement of South Africa's racial conflict, business leaders are interested in Mandela's views on the South African economy after apartheid. His African National Congress (ANC) adopted a platform in 1955 that calls for the nationalization of monopoly industry, the banks, and the mines. Since his release from prison in February, Mandela has endorsed nationalization, though he has assured the South African business community that an ANC government would not take any precipitous action that could destabilize the economy. "The view that the only words in the economic vocabulary that the ANC knows are nationalization and redistribution is mistaken," Mandela told business leaders in Johannesburg.

Mandela will have little persuading to do here on the continuation of sanctions because under the 1986 Comprehensive Anti-Apartheid Act the U.S. measures cannot be lifted until specific segregation laws are eliminated in South Africa. As a result, according to Africa specialist and former United Nations ambassador Donald F. McHenry, now a professor at Georgetown University, the focus of the Friday meeting with business leaders will be Mandela's vision of the future South African economy.

"The thing I'm particularly interested in is how he can encourage U.S. business community to be involved in a productive way in a post-apartheid South Africa," said Carl McCall, vice president for government relations at Citibank. "What I would like to hear is that Mandela sees an important role for the American business community and that he sees it in a partnership with the new democratic South Africa."

William Hayden, a senior managing director of the securities house Bear Sterns, said "I'm not going to change the political climate in South Africa. I can't march and jump up and down. But I do understand capital flows."

Like many of the firms invited to the meeting, both Bear Stearns and Citibank have come under activist pressure in this country to cut any connections with South Africa. Last year Bear Stearns stopped handling South Africa gold stocks for clients after Los Angeles threatened to disqualify the firm from handling the city's municipal bond business.

Citibank was one of several big U.S. banks that refused to roll over loans to South African companies in August 1985, setting off a debt crisis there. Although it subsequently rescheduled the loans, its South African loan portfolio has dwindled from about $800 million to $640 million, all of which South Africa has agreed to pay before the end of 1997. But many anti-apartheid activists complain that Citibank should have driven a harder bargain to pressure the Pretoria government.

While the ANC is wary of the embrace of American business, it does not want to alienate it either. "Mandela and company see that the Third World aspect of South Africa is going to need a lot of development," McHenry said.

People familiar with the ANC and its leaders expect Mandela to explain his position on nationalization in light of South Africa's already highly concentrated economy. According to Stephen Lewis, an economist and president of Carleton College, the South African government already owns more than 40 percent of the country's fixed capital assets. One company, Anglo-American Corp., has controlling equity interests in companies that make up about half of the Johannesburg Stock Exchange's total capitalization. Half a dozen other companies control an additional 20 to 30 percent of value of the stock exchange.

"To tell Africans that they can now start vegetable stands in the townships is just not acceptable," said Knight of the American Committee on Africa. McHenry agreed: "If there were more understanding of the economic situation in South Africa, Mandela's earlier comments on nationalization would have been greeted with yawns. South Africa already has very heavy state control of important segments of the economy and six or seven very powerful companies."

Many of the business leaders Mandela will meet are likely to be sympathetic to his views.

"The American business community has to be open minded," McCall said. "It is doing that in Eastern Europe where it is willing to do business with ex-communists. It should be able to do business with ex-revolutionaries in South Africa."

McHenry noted, however, that persuading American business to reinvest when the time comes may be difficult. "Investment decisions will be quite different from before," McHenry said. "South Africa has always been an artificial investment climate. It will become more normal {after apartheid} and there will be more normal considerations." If wages for black workers rise, for example, and if the price of gold sags, some gold mines could become marginal investments, McHenry said. "Things will be difficult even with the best of good faith. They have a marvelous base to build on, but it is still going to be difficult."

Harlem businessman Lee Dunham, who owns eight McDonald's franchises in New York City and New Jersey, said he does not care if anything concrete comes out of the Friday meeting. "It is so rare that we have a person of his stature," Dunham said. "Just to be in the same room with a person like that is going to be a thrill even if I don't get to ask anything."