LAWYER EASILY WINS NOMINATION TO REPLACE PEPPER IN THE HOUSE

Gerald Richman, a lawyer who drew sharp criticism for remarking that he was running for ''an American seat,'' decisively captured the Democratic nomination today in the race to succeed the late Representative Claude Pepper.

Mr. Richman, a 47-year-old former president of the Florida Bar Association making his first run for office, defeated Rosario Kennedy, a Cuban-born former Miami City Commissioner who gave up that job to run in the special election. With all of 146 precincts reporting unofficial returns, Mr. Richman had 14,411 votes, or 61 percent, and Ms. Kennedy had 9,226 votes, or 39 percent.

The Republican candidate in the special election, which will be held Aug. 29, is State Senator Ileana Ros-Lehtinen, a 37-year-old Cuban-born educator. Mr. Pepper held the seat for the Democrats for 27 years, until his death on May 30 at the age of 88. Come-From-Behind Victory

Mr. Richman stunned Ms. Kennedy, the Democratic front-runner, with a 146-vote victory in the Aug. 1 primary, in which five other Democrats were eliminated. Ms. Ros-Lehtinen won the four-way race for the Republican nomination with 83 percent of the vote. Her campaign manager is Jeb Bush, the President's son.

Little difference on issues emerged between Ms. Kennedy and Mr. Richman in their runoff, which was dominated by discussion of ethnic divisiveness, qualifications and ability to defeat Ms. Ros-Lehtinen.

Mr. Richman has said repeatedly, ''This is an American seat,'' explaining that he rejects the assertion by Lee Atwater, the chairman of the Republican National Committee, that it is time to elect the first Cuban-American to Congress. Mr. Richman says that he is ''for all the people'' and that the election should go to the best-qualified candidate.

But the Dade County Fair Campaign Practices Committee was critical of Mr. Richman's campaign, and The Miami Herald called it ''naked, deliberate, bigotry'' and endorsed Ms. Kennedy. 'Divisive Campaign'

Ms. Kennedy, who was 14 when she left Cuba, implied in a debate on Saturday that Mr. Richman's campaign tried to exploit her Spanish accent. ''When are you going to stop this type of divisive campaign?'' she asked.

Ms. Kennedy criticized Mr. Richman, who raised money for Democratic candidates in 1988, for contributing $2,000 to the Bush campaign. Mr. Richman said he attended a Bush dinner at a friend's request, and his campaign countered that Ms. Kennedy had campaigned with Dan Quayle when he was running for Vice President. Her campaign said she had appeared with Mr. Quayle in her role as a City Commissioner.

The district has 71,620 registered Republicans and 100,198 registered Democrats. More than half the Republicans and about a sixth of the Democrats are Hispanic.

In the primary on Aug. 1, Ms. Kennedy carried predominantly Hispanic precincts and Mr. Richman won in Miami Beach, which is dominated by Jewish and elderly voters.

Jo Ann Pepper, the late Congressman's niece, and two black candidates, Marvin Dunn and Sonny Wright, carried the district's black neighborhoods. All three endorsed Ms. Kennedy.