U.S. Ambassodar Lawrence Pezzulo warned today that any attempt to destabilize Nicaragua's new revolutionary government would be contrary to U.S. policy and that of other nations in the hemisphere.

Pezullo's statement came less than two days after Sandinista leaders here charged that Somoza loyalists were attempting to organize armies in the United States and Honduras to overthrow the government recently installed in Managua.

The ambassador's written statement was designed, in effect, to quiet fears on the part of Sandinista leaders of U.S. intentions. It also undermines the hopes of pro-Somoza elements that the United States might consider helping them in a counterrevolutionary invasion, as it did anti-Castro Cuba in what became the ill-fated Bay of Pigs invasion.

Sandinista leader called on the United States Saturday to prevent "military adventures" by pro-Somoza leaders, many of whom are now in Miami.

"The United States is providing humanitarian assistance to help satisfy emergency needs in Nicaragua and is prepared to assist the Nicaraguan government in its economic recovery efforts," Pezzullo said today.

"Any attempts to destabilize the situation or provoke violence would be looked upon by the United States as contrary to" resolutions approved by the Organization of American States the ambassador's statement said.

It was also pointed out that foreign citizens living in the United States could be expelled for political activity such as plotting against the new Nicaraguan government, if such activities were proven.

Pezzullo's statement was in first since returning Saturday. He left 10 days ago when Somoza's designated successor, Franciso Urcuyo briefly refused to turn over power to the new government as had been negotiated.

Pezzullo is scheduled to formally present his credentials to the ruling revolutionary junta Tuesday and then begin work on building a new relationship with the government here, which has said it wants friendly relations with the United States but is known to be highly suspicious of U.S. intentions.

The American strategy appears to be one of assuming a relatively lowkey role in its public activities and statements, expect for the humanitarian and economic assistance it is providing the war-shattered country. The hope seems to be that the United States, by leading these international efforts, will garner sufficient goodwill among the Nicaraguan people to overcome the U.S. association with 46 years of Somoza family rule.

(In Washington, the State Department said it is willing to consider an informal request for the United States to provide arms to the revolutionary government. Interior Minister Tomas Borge said Sunday he has requested military aid in a private meeting with Pezzullo.

(Department spokesman Hodding Carter said yesterday that a formal request had not been received, but he added, "We would be willing to consider a formal one and will take under a consideration the informal one that we have in hand." He said the Nicaraguans had not been very specific about the type of military aid they want but had discussed the possibility of U.S. training as well as arms sales.)

The United States currently has about $25 million in loans approved for Nicaragua that were negotiated with the previous government. This money, as well as substantial amounts of new loans and grants, could begin flowing within a short time to help rebuild the economy here if Washington and Managua can agree on how the money should be spent. More than $3.5 million in food, medicine and other U.S. humanitarian assistance already has arrived and more is on the way. This assistance, reporters have been told, will continue to be sent unless the new government here decides to stop it.