A major American effort to topple Nicaragua's revolutionary Sandinista government would be met with eruptions of greatly stepped-up violence from Guatemala south to Panama, senior Sandinista officials here assert.

"The people of Costa Rica, of Honduras, of Panama and of the region feel that the Nicaraguan revolution is their revolution. They would respond to attempts to smash the Nicaraguan revolution," said Commander Bayardo Arce, one of the nine members of the Sandinista Front's powerful National Directorate, to which even the government's executive junta is effectively subordinate.

At the same time, the officials, including a member of the three-man government junta in addition to Arce, said they are working to avoid the confrontation with the United States that they fear will be precipitated by the deteriorating situation in El Salvador's civil war. Specifically, they said they fear that Salvadoran guerrillas will succeed in their announced plans to stop U.S.-backed elections there March 28.

"If the elections are a failure," Nicaraguan junta member Sergio Ramirez said, "we think someone is going to pay, and it's going to be us."

The Nicaraguans cited their public offers to talk with Washington and attempts to moderate guerrilla plans for a major offensive against the Salvadoran government this month as measures they are taking to avert the crisis.

These officials steadfastly denied Reagan administration charges that Nicaragua is supplying arms to the Salvadoran guerrillas, but one Sandinista leader did say that in the past his group showed the Salvadoran rebels how black-market arms were procured for the 1978-1979 insurrection here.

The Reagan administration has insisted on a cutoff of the alleged arms supplies as a requisite for better relations with Nicaragua. They have gone downhill since U.S. aid was cut off over this same question a year ago.

In recent weeks there have been growing reports of U.S. plans for covert action against the Sandinistas as well as American military maneuvers that the leadership here views as threatening.

In the event of major military action against Nicaragua, Arce said in an interview, "who can guarantee that the Costa Rican people or the Panamanian people will be quiet? Who can guarantee that the Guatemalan opposition will not be increasing its activity? Who can guarantee that all Central America will not be burning?"

This theme was echoed by junta member Ramirez in a separate interview yesterday and Defense Minister Humberto Ortega in an address last night.

"We not only know how to resist, we know how to beat our enemies," Ortega warned as he addressed a rally marking International Women's Day. "This war, in case of an intervention, will not be only of Nicaragua but of Central America."

Another senior Sandinista official said that in case of any intervention that appeared directed at the complete destruction of the Sandinista revolution, "our defense will not be limited to our national territory. It will be expanded throughout the region. We will have to think about not only how to resist, but how to destroy the enemy and his rear guard in the region."

The Sandinistas did not specify just how they would go about this, but fledgling underground revolutionary organizations that have sprung up in both Honduras and Costa Rica during the past 18 months are believed by officials in those countries to have major ties to the Sandinistas. The Nicaraguan revolutionaries are open about their political and ideological affinities, if not material support, for such movements.

But despite their constant references to regional war, officials here cited it as an alternative they hope to avoid. Unless there is a major foreign incursion into their territory, "we will bite our lip. We won't attack anyone," Arce said. "We will not fall into a trap."

The Sandinistas portrayed themselves as caught in a squeeze between an increasingly bellicose United States and Salvadoran guerrillas intent on pushing their own revolution to a point where hostilities could easily get out of control.

The Reagan administration, which has invested major amounts of money and prestige in backing the current Salvadoran regime to stop the advances of Marxist revolutionaries in the hemisphere, considers the elections a key political element in the war.

"We know the path we're on," Ramirez said. "We know the government of the United States is making a confrontation over the alleged fact that we are sending arms to El Salvador. We know the United States' interest in the situation there. We are a very realistic people," he continued, adding that Nicaragua's leaders do not want to intervene in their neighbors' affairs but to consolidate their own troubled revolutionary process.

"If not," said Ramirez, "we would put Central America in flames. Because we have the means to send arms to Guatemala, Panama, Costa Rica. It is not so difficult."

Arce said that because of the political impact of such a move, it would be self-defeating for both Nicaragua and the Salvadoran rebels if the Sandinistas were supplying them with significant shipments of arms.

"What we have told the Salvadorans is how we handled the traffic ourselves and introduced them to some merchants who . . . say, 'Do you want them here or delivered?' There are even some of those in the United States," Arce said.

But Arce and the other Sandinistas insisted that despite such friendly advice and relations in the past, the Sandinistas are now frustrated with the Salavadoran guerrillas' refusal to heed their current counsel and pull back from a planned attempt to mount a "popular uprising" this month.

The Sandinistas set up an interview for Washington Post reporters with Ferman Cienfuegos, a top Salvadoran guerrilla commander who was in Managua on Friday, saying they did that so the reporters could "hear for themselves" the way the Salvadorans are talking.

What Cienfuegos said was, "It's our own decision."

The Sandinistas listed several new U.S. actions, some of which are publicly known and some of which they say they learned about from the intelligence services of "friendly countries."

Arce listed virtually unprecedented NATO naval maneuvers in the Caribbean just before the elections, the stationing of an intelligence-gathering U.S. Navy destroyer in the Gulf of Fonseca, reported discussions between Washington and Honduras about possible U.S. military use of Honduran facilities in case of a regional emergency and, Arce alleged, flights of 10 U.S. Hercules transport planes into the Honduran capital with what the Sandinistas presume to be military cargo at the end of February.

Ortega, in his speech last night, dated serious increases in anti-Sandinista activities from October and included among them material support for armed bands of Nicaraguan ex-National Guardsmen defeated in 1979, frequent contacts among the "reactionary" military chiefs of Guatemala, El Salvador and Honduras, the creation of the Central American Democratic Community that excluded Nicaragua, and spy flights over Nicaragua..

The Sandinistas said that they are depending on American public opinion, the international media--which they also sometimes accuse of aiding the "counterrevolution"--and the U.S. Congress to restrain a Reagan administration that they picture as either unwilling or unable to control the forces they say are about to be unleashed against them.

"The people of the United States have become the principal element to stop any aggression against us or intervention in Central America," said Ramirez. If that were not the case, he concluded, "we think people like Secretary of State Alexander M. Haig and U.N. Ambassador Jeane Kirkpatrick would have long ago invaded us."