Nicaraguan leaders see a pattern of organized violence and subversion undermining their three-year-old leftist revolutionary government.

During the past three months, especially since the beginning of July, sporadic incidents of protests and sabotage against the Sandinistas' rule have begun to be replaced by a pattern of clashes and even pitched battles, and there are growing fears that the escalating violence inside Nicaragua--and in the region--is moving beyond anyone's power to curb.

Nicaraguan leaders sharply criticize both the neighboring government of Honduras and the Reagan administration, which provides extensive military aid to Honduras, for abetting these actions.

Daniel Ortega, the ranking member of the government junta here, told two American reporters last week that the Sandinistas want to pursue a "revolutionary project" that includes political pluralism, a mixed economy and nonalignment with either of the superpowers. But he said that they have "encountered a serious obstacle called the United States."

"The actions of the current U.S. administration are directed at provoking the Sandinista revolution to radicalize and, because of that, to destroy the possibility of this project," said Ortega.

"The current U.S. administration would find it easier to fight against a radicalized revolution than against a revolution with the characteristics that Sandinism defends," Ortega continued. "All this has to do with the fear that the U.S. administration has of change in the Central American region . . . .

"But despite all this," Ortega said, "we believe that the project continues to be viable."

To date the Sandinistas have taken no concrete steps toward elections, which have been put off at least until 1985. Under a state of emergency declared March 15 after saboteurs destroyed two major bridges, they have imposed rigid press censorship.

The Sandinistas occasionally have arrested and often have alienated major businessmen with their legislation and economic policy. They frequently attack religious leaders who question their actions, and opposition political parties are regularly harassed and intimidated.

The Sandinista leaders openly admire the Cuban revolutionaries, seeking their advice and help, and have established warm relations with the Soviet Bloc.

Ortega maintained, however, that if the threat posed by the Reagan administration were taken away, Nicaragua could return to "normal" and that, for example, "the elections are going to be possible in Nicaragua to the extent we can achieve a minimum of stability, a minimum of security."

American diplomats here deny or refuse to discuss the allegations of U.S. support for anti-Sandinista insurgents. They say, however, that the overt economic and political pressures put on the Sandinista government are a reaction to Nicaragua's extensive political radicalization and its alleged material and logistical support for leftist guerillas in El Salvador and elsewhere in the isthmus.

The Reagan administration has cut off direct U.S. aid to the Sandinista government, impeded loans from international organizations and attempted to increase Nicaragua's political isolation in the region through diplomatic moves while rapidly increasing military aid to its neighbors, especially Honduras.

"Our policy," according to one senior U.S. diplomat, "is to try to persuade the Nicaraguan government to cease and desist its destabilizing activities through the rest of the region and return to the original goals of the revolution." One Western diplomat noted that intentionally radicalizing the Nicaraguan government "only makes sense if you think that radicalized state will be of short duration."

"I believe the goal is moderation," he concluded.

The fact that the Sandinistas recently have been making conspicuous efforts to nurture and sustain ties with "third powers" such as France, Mexico and Venezuela is seen by some diplomats and by internal opponents of the government as evidence that the pressure being applied by Washington is having positive effects.

Meanwhile, however, there are growing fears about the rapidly escalating violence inside Nicaragua, whatever its source.

"I think the United States has enormous influence in Central America," said one foreign observer with extensive experience in the area. "But I think forces are unleashed here that are just too hard to control. Too many people have too many guns here now. Even if the Cubans and Russians back off, you're in for considerable turmoil here."

For two years leftist guerrillas who clearly enjoyed Sandinista sympathy and, as they say here, "solidarity," as well as alleged Nicaraguan help with armament and communications, have been waging war in El Salvador and Guatemala.

More recently, Honduran and Costa Rican leaders have charged that Sandinistas played a part in the formation of terrorist groups now emerging in those countries.

But during the past three months, especially this month, Nicaragua itself again appears to have become a scene of serious fighting.

The government admits that at least 39 Sandinista militiamen, policemen and soldiers have been killed in July alone. It claims to have killed 75 "counterrevolutionaries."

Cmdr. Javier Pichardo, in charge of the Sandinista Army in northwestern Nicaragua and responsible for patrolling about half of the border with Honduras, said last week that there are at least 17 rebel camps just across the line.

Pichardo recited a litany of anti-Sandinista "aggressions" since the beginning of 1981, ranging from alleged violations of Nicaraguan air space (150) to cross-border cattle rustling (234 incidents), and shoot-outs (45).

In the most recent incident, on Saturday, anti-Sandinista insurgents who apparently came from across the Honduran border, seized the village of San Francisco del Norte for 2 1/2 hours and killed 14 militiamen.

Foreign Minister Miguel d'Escoto, who traveled by helicopter to the scene of the attack with reporters and several foreign ambassadors, bitterly criticized Honduras and the United States.

Reporters taken on a tour of the border area around Guasaule on Wednesday ran into repeated reports of conflicts, many of them short-lived skirmishing, although last Monday a light plane reportedly launched an unsuccessful rocket attack on petrochemical storage tanks in Corinto.

To the east, in the steamy forests of Zelaya, the fighting appears much more serious and to have grown worse since a series of confrontations with anti-Sandinista rebels last winter provoked the forced relocation of 10,000 Miskito Indians from the banks of the Coco River.

Reporters have virtually no access to that region.

While in the west Pichardo said most of the insurgents his troops are fighting appear to be former members of the defeated National Guard of dictator Anastasio Somoza, the Zelaya commanders refuse to say exactly who makes up the forces they engage.

They claimed that the leaders of the insurgents in their area are Moravian priests who traditionally work with the Miskitos and that some of these were themselves Indians.

Much of the heaviest fighting this month began at a settlement called Seven Benk about 30 miles west of Puerto Cabezas and lasted from July 4 to July 18, according to the Zelaya commanders. As they charted the action on a map at a press conference, they showed it moving into the region called Tasba Pri, especially around the large temporary camp at Truslaya, where most of the Coco River Miskitos were relocated.

The Sandinista commanders said they "could not confirm" that the insurgents used Truslaya as a source of supply or manpower, but that whoever they were up against was well-armed and well-trained.

Managua newspapers last week headlined the announcement of a joint U.S.-Honduran military maneuver scheduled to begin Monday. The Foreign Ministry complained that the operation would "increase the tension the region is living."