The Sandinista leadership expressed hope today that congressional rejection of U.S. military aid for rebel forces here was a "first positive step" toward ending Reagan administration pressures against Nicaragua.

In a cautious victory claim early today, the revolutionary government also renewed its call for resumption of direct negotiation with the United States and underscored its "firm and irreversible determination to never accept any kind of dialogue" with the U.S.-backed insurgency as sought by President Reagan.

The Sandinista statement was worked out in prolonged conversations after Tuesday's House of Representatives vote denying Reagan's request for $14 million more military aid for the rebels, and before Wednesday's defeat of a compromise proposal.

Reacting to news of the House's definitive rejection Wednesday, the government reiterated its decision to send home 100 Cuban advisers and announced release of 107 prisoners held on charges associated with the U.S.-backed insurgency.

Aside from these announcements, the Sandinista leadership avoided adding to its earlier praise for the disposition in Congress of Reagan's request for more rebel aid. Nicaragua President Daniel Ortega earlier had pledged to make a "gesture" if the $14 million in additional aid was rejected. The government's announcement tonight appeared to be designed to fulfill that promise.

The tone of the earlier communique reflected uncertainty over the voting's practical meaning for the guerrilla war under way here since 1981. Officials here consistently have predicted that the administration will find ways to get more money to rebel forces even without the direct CIA funding that channeled about $80 million to the insurgency until a congressional cutoff last spring.

The Sandinista reaction also demonstrated an apparent desire to avoid obvious crowing over the political setback for Reagan's strongly expressed endorsement of the rebels as the most effective way to counter the six-year-old Sandinista revolution. Sandinista officials previously have made it clear, however, that they considered the political symbolism of the vote, as a reflection of U.S. political support for or against the rebels, more important than the $14 million, particularly since Reagan had defined the battle as critical.

In Tegucigalpa, Honduras, Frank Arana, a spokesman for the Nicaraguan Democratic Force, the largest guerrilla group fighting the Sandinistas, said rebel leaders would continue seeking arms and supplies through private organizations and friendly governments, Reuter reported.

Key Sandinista leaders followed House and Senate proceedings via telephone connections with the Nicaragua Embassy in Washington, a government official said. A well-informed diplomat said Foreign Ministry officials here had been awaiting the crucial vote in hopes that it would demonstrate that Reagan cannot continue his policy of open military pressure on Nicaragua and would support their contention that the policy violates international standards of conduct.

The political fallout of the dramatic congressional action in Washington is also seen as particularly important in Honduras, which in cooperation with the United States has offered a haven and logistical support to the Nicaraguan Democratic Force. A number of Honduran military officers, including Gen. Walter Lopez, the armed forces commander, have expressed concern at their role in helping the rebels if direct U.S. financing and clear political endorsement are withdrawn.

U.S. sources have calculated that 6,000 of the Nicaraguan Democratic Force's estimated 12,000 armed men pulled back into camps within Honduras as money and supplies ran short during the past several months despite fund raising by rebel political representatives. The insurgent military commander, former colonel Enrique Bermudez, has predicted fund raising will become even more difficult without clear-cut U.S. political backing and at least the promise of resuming U.S. financial support.

The other main guerrilla force, headed by former Sandinista commander Eden Pastora in camps along the border with Costa Rica, has been only partially active since U.S. funds ran out last summer.

Apparently with Honduras and Costa Rica in mind, the Nicaraguan government said:

"Nicaragua reiterates to Central American governments, and especially to those that have been involved in any way with the war being waged against our people, its disposition to subscribe as soon as possible to the Document for Peace and Cooperation in Central America proposed by the Contadora group."

The Contadora peace effort has sought to work out an agreement among Central American countries pledging them to peaceful relations, noninterference in one another's affairs and dissociation from foreign military partnerships.

The reaction of the Sandinista leadership also seemed designed to buttress objections posed by some U.S. congressmen who, although expressing disapproval of the Sandinista government, maintain that U.S. funding of military action against another government violates international law. Sandinista officials long have voiced hope that because of these considerations, the American people and Congress eventually would come to oppose Reagan's support of the rebels.