Secretary of State Cyrus R. Vance, lamenting the bloodshed in Nicaragua as a "war of national destruction," yesterday called for President Anastasio Somoza's replacement by a "transitional government of national reconciliation," and, if necessary, the dispatch to Nicaragua of an inter-American peacekeeping force.

The secretary's unprecedented public call for ousting the leader of a government with which the United States has technically normal relations was contained in a speech and a draft resolution presented by Vance to a meeting of Organization of American States foreign ministers.

The meeting of the 27-nation hemispheric body was called at the urgent request of the United States to deal with the escalating Nicaraguan civil war. While not mentioning Somoza by name, Vance made the U.S. position unmistakably clear when he said:

"We must seek a political solution which will take into account the interests of all the significant groups in Nicaragua. Such a solution must begin with the replacement of the present government with a transitional government of national reconciliation, which would be a clear break with the past."

He then urged the OAS to send a delegation immediately to Nicaragua to help form a transitional government "leading to free elections in which the will of the Nicaraguan people can be freely expressed."

The leadership of the Sandinista forces, now fighting Somoza, last night rejected Vance's proposal and vowed, in a communique broadcast by Costa Rica Radio, to continue the war "until we win or die."

To put teeth in the proposed actions, Vance said the OAS should insist on a cease-fire within Nicaragua, a halt to shipment of arms to the contesting factions there, and, if OAS members decide it is required, a peace force "to help restore order and to permit the will of the Nicaraguan citizens to be implemented in the establishment of a democratic and representative government."

Vance did not specify whether the United States would be willing to commit U.S. troops to the peace force. However, the hostile reaction the idea triggered among Latin American ministers last night made clear that this aspect of the U.S. proposal has no chance of adoption by the OAS at the present time.

U.S. officials said privately that their main interest for the present is in getting the OAS behind some expression of sentiment that Somoza should go and in injecting an OAS presence into the Nicaragua situation.

The peace force, these officials added, is a concept that can be considered anew at a later time if events in Nicaragua dictate that it is needed.

At that time, the officials said, the OAS could thresh out the question of whether U.S. troops should included in such a force or whether it should be limited to troops from other hemispheric countries, as the United States would prefer.

Vance's proposal brought into the open the policy goals that U.S. officials have been advocating privately since last September, when tensions in Nicaragua erupted into civil war between Somoza's National Guard and the guerrillas of the Sandinista National Liberation Front.

Until now Washington had pursued its effort to induce Somoza to step aside through behind-the-scenes maneuvering.Its actions had been dictated by fears of offending Somoza's supporters in Congress and of provoking charges within Latin America that President Carter was violating his pledges not to interfere in the affairs of other countries.

However, the recent renewed fighting in Nicaragua convinced administration policymakers that Somoza's days in power are numbered and that, unless urgent steps are taken to impose a moderate solution, the result will be a Sandinista takeover.

Such an outcome currently is regarded as unacceptable by the administration, because at least some of the groups making up the Sandinista front are regarded as Marxist and pro-Cuban. Washington fears that these forces would emerge on top in any Sandinista government and turn Nicaragua into a Cuban-controlled bastion in Central America.

Vance's speech also marked a historic instance of reversing U.S. foreign policy - an open, definitive break with the Somoza family, which has controlled Nicaragua for 46 years.

The United States put Somoza's father, Anastasio Somoza Sr., in power by installing him as head of the American-created National Guard when U.S. marines ended a long occupation and withdrew from the country in 1933.

Four years later, the Somoza father seized the presidency, and the family has run Nicaragua as a personal fiefdom ever since. For most of that time, the United States trained and armed the National Guard in exchange for the Somoza's maintaining a pro-American, anti-communist stance in Central America.

The first fissures in this relationship came with the Carter administration's advocacy of a strong human rights policy. That led Washington to pressure Somoza to ease his strong dictatorial grip - pressure that, in turn, helped stir the unrest building up in the country.

Vance did not spell out how the United States belives Somoza can be induced to step aside. Instead, he said only, "We must call upon all Nicaraguan leaders to recognize this avenue to a lasting peace and to take the steps necessary to carry it out."

Privately U.S. sources said there is little hope of the collective OAS membership, with its ingrained hostility toward intervention, adopting all aspects of the U.S. plan.

But, the sources added, the United States is hopeful that a consensus now exists among the region's democracies and many of its previously pro-Somoza military regimes that hemispheric peace requires his departure.

The U.S. strategy, they said, is based on the hoped that the speeches and debate at the meeting here will make this clear to Somoza.

This U.S. hope seemed to be borne out by the speeches made last night by the Latin American ministers.

However, the sources cautioned, it probably will be two or three days before it becomes clear whether the meeting can produce consensus on the two priority U.S. goals: a call for Somoza to step down and agreement to send an OAS commission to Nicaragua to begin laying the groundwork for a transitional government.

Late last night Panamanian Ambassador Juan Antonio Tack said his government is recognizing a five-member provisional government announced last week by the Sandinistas as the legitimate representative of the Nicaraguan people. CAPTION: Picture 1, Cpl. Lorenzo Brenes of Nicaragua's National Guard tells foreign reporters that he did not kill Bill Stewart. AP; Picture 2, Nicaraguan troops advancing in Managua comes upon a former rebel barricade. UPI; Picture 3, Nicaraguan rebels man recoilless rifle in action near La Virgen Wednesday. By Nicaraguan soldier Emilio via Associated Press; Picture 4, Sandinistas guerrillas lead away a government soldier captured in Sapoa. By Nicaraguan soldier Emilio via The Associated Press