The United States tonight vetoed two Security Council resolutions, one on Nicaragua and the other on Israel, that were supported by nearly all council members including most of America's closest Western allies.

The first veto came on a resolution that would have implicitly appealed to the United States to refrain from the use of force--overt or covert--against Nicaragua. The vote was 12-1, with Britain and Zaire abstaining.

Within an hour, U.S. Deputy Representative Charles Lichenstein cast his second veto, this one on a Jordanian resolution that would have denounced Israeli actions in the West Bank and called on Israel to rescind its ouster of three Palestinian Arab mayors there. The vote was 13-1, with Zaire abstaining.

France, Ireland, Japan and Spain joined the Third World and the Soviet Bloc in backing the Nicaraguan resolution. Britain added its vote against the United States on the Middle East.

After the vote on the Nicaraguan resolution, Lichenstein insisted that "the door to negotiation and reconciliation" with Nicaragua "remains open."

The defect in the resolution, he said, was that it failed to identify certain key elements of the urgent problems facing Central America. These problems, the United States charged, were created in major part by the intervention of Nicaragua's revolutionary Sandinista government in the affairs of its neighbors.

Nicaraguan Foreign Minister Miguel D'Escoto also reaffirmed "Nicaragua's readiness to embark as soon as possible on a fruitful dialogue with the United States."

But he charged that "what has been vetoed here is not a resolution--what the United States has done is to veto the fundamental principles of the U.N. Charter."

Neither the United States nor Nicaragua was cited by name in the resolution, which was put forward by Panama, but the implication was unmistakable. It would have appealed to all parties to negotiate a peaceful solution to the problems of Central America and the Caribbean, and it cited various principles of the U.N. Charter such as territorial integrity, the nonuse of force, nonintervention in domestic affairs and the peaceful settlement of disputes.

Lichenstein criticized the resolution for quoting selectively from U.N. Charter principles, a selectivity, he said, that "breeds a cynicism that harms the U.N., undermines the inter-American system, and harms the search for peace."

Informed U.S. administration officials said last month that President Reagan had authorized covert paramilitary operations against Nicaragua, leading the Central American government to accuse the United States of planning an invasion and to bring the issue to the Security Council.

U.S. Ambassador to the United Nations Jeane J. Kirkpatrick reaffirmed to the council that Nicaragua's fear of an invasion is "groundless." But she offered no reassurance on the American use of indirect or covert force against the Sandinista government.

She later flew to Washington to consult on the vote and on a possible American amendment that would have referred the issue to the Organization of American States.

American officials here said such an amendment would have made the resolution acceptable to Washington. Nicaragua opposed the change, however, and in the end it was not put forward.

D'Escoto told the council that Nicaragua was ready to talk to the Americans under the formula proposed by Mexico last month, which was reportedly accepted in principle by both sides.

But he noted that 12 days had elapsed without an American reply setting a specific date for the meeting, which reportedly will take place in Mexico City. D'Escoto said he would be unavailable for such talks until mid-April, because he leaves Saturday for Kuwait to attend a meeting of the coordinating board of the nonaligned group of nations.

The prime reason for America's veto of the Middle East resolution appeared to be a desire not to irritate Israel in advance of its scheduled withdrawal from the Sinai on April 25.

Lichenstein, in explaining his veto, did not refer to the Sinai but said that the resolution "uses denunciatory language and does not take account of the complexity of the West Bank problem."

He said the resolution should have urged restraint on the parties to avoid any new outbreak of violence and should have made reference to council resolutions 242 and 338, which outline a negotiated Middle East settlement.

The United States, he said, is deeply concerned about the West Bank disturbances and about the dismissal of the elected officials there. But he noted that the Geneva convention on the protection of civilians in wartime, which was cited in the resolution, gives the occupying power the right to dismiss local officials.

He concluded that the resolution would lead away from a peaceful solution, so the United States was compelled to veto it.

The Arab nations were divided tonight on whether to pursue the issue in the General Assembly. If it were to be raised there, the question of Israeli representation in the assembly would also arise. And the United States has threatened to walk out of the assembly--and perhaps stop paying its share of U.N. costs--if Israel is excluded from the body.

As a result, the moderate Arabs are reluctant to press the issue, while the more radical Arab countries would prefer such a confrontation.

Earlier, Kirkpatrick criticized Nicaragua for its "massive intervention" in the affairs of its neighbors. The real issue in Central America, she said, "is a conflict between two concepts of organizing society, two ideologies, one democratic and the other totalitarian." She cited the elections in El Salvador as an example of a democratic approach, and the refusal of the Sandinistas to hold elections as the totalitarian approach.