Vice President Bush paused in his courtship of conservatives tonight to celebrate Republican Party gains and issue a warning to the GOP that it must do more to attract new voters.

In remarks to the annual Lincoln Day dinner of the New York County Republican Committee, Bush said:

"If we're to be a majority party, we must make a home for people from all groups and all regions. I believe we've got to reach out. We've got to include, not exclude."

He added, "We still have much to do."

His remarks appeared to be a reference to polls showing continuing disapproval of President Reagan among many black Americans.

Republican political strategists have said the GOP needs to do more to address blacks' concerns if it is to obtain majority status.

Bush said Republicans have done well among some traditionally Democratic and independent voters in recent years.

"We've done well in the South. We've captured our share in the big cities. We're winning young voters overwhelmingly. We're a major contender for the vote of many members of labor unions," he said, adding that these gains were because of Reagan's policies. "We must preserve momentum."

The vice president traded charges recently with New York Gov. Mario M. Cuomo, a potential 1988 presidential candidate, over issues of ethnicity in politics, but Bush did not mention the Democratic governor tonight.

Bush has been speaking recently to conservative groups as part of a strategy to compete with rival presidential hopeful Rep. Jack Kemp (R-N.Y.) for their allegiance.

Bush's speech to the Conservative Party here two weeks ago drew sharp criticism from, among others, syndicated columnist George F. Will, who accused Bush of pandering and misrepresenting Cuomo.

Bush is planning to perform Republican Party duties for a while but has scheduled speeches to several other groups of conservative activists later this spring.

Speaking tonight to 1,500 persons at a $300-a-plate dinner at the Waldorf Astoria hotel, Bush alluded to problems bedeviling the party as well as its successes.

He noted "a rising chorus in the Congress saying that we must have massive reductions in defense spending."

Although Bush did not say so, Republicans as well as Democrats have issued such calls for a slowdown in defense spending.

"We believe that defense spending can and must be brought down further," Bush said. "But there's only one safe way to do it. And that is to get an agreement from the Soviets for mutual and verifiable reductions in nuclear weapons."

The vice president said Reagan's defense policies have been "critical in uniting" Republicans and "dispelling some myths about the party."

"The approach of the late '70s -- unilateral cancellation of weapons systems without demanding parallel Soviet reductions -- failed to produce a reduction in the threat to the peace and security of the United States," he said.

"It might surprise you to learn," Bush said, "after the reductions the president agreed to in negotiations with the Congress over the last year, the 1986 defense budget is actually smaller than it would have been under the last plans prepared by President Carter."

Bush said it was a "wonderful moment for human rights and freedom" when Soviet dissident Anatoly Scharansky was freed this week.

He said the administration had put human rights in the Soviet Union "at the top of the U.S.-Soviet agenda, and frankly that has helped to win Scharansky's freedom."

Although "we rejoice in the release of Scharansky," Bush said, "and though we took great happiness when Ethiopian Jews were permitted to go home, we've got to remember there are three million Jews in the Soviet Union who want freedom. . . . "

This remark brought perhaps the strongest applause from an audience that seemed to greet Bush warmly but without wild enthusiasm.

Bush, here briefly to address the traditional GOP dinner, returned to Washington tonight.