MANAGUA, NICARAGUA, FEB. 4 -- A skeptical and tough-talking President Daniel Ortega today minimized the effect of last night's vote in the House of Representatives against new aid for the Nicaraguan rebels, saying it "doesn't mean the war is over," and called on Nicaraguans to "complete the total defeat" of the rebel forces.

Far from praising the congressional decision or offering new concessions under a regional peace pact, Ortega bluntly insisted on bilateral security talks with Washington, accused neighboring El Salvador and Honduras of failing to comply with the accord and warned Nicaragua's opposition political parties to "straighten out."

The starkly unconciliatory tone of Ortega's nationally broadcast, midday address and press conference seemed to reflect deep doubts among senior Sandinista leaders that last night's House vote would result in a lasting change in Washington's policy toward Nicaragua.

His 30-minute speech to also appeared tailored to meet the concerns of the more militant members of the Sandinista leadership who fear that Nicaragua has made too many concessions in the peace process.

Ortega stressed the narrow margin, 219 to 211, by which the administration's $36.2 million aid package was defeated.

He also referred repeatedly to a meeting he said was in progress this morning in Washington where, he speculated, President Reagan and his top advisers would seek ways to circumvent the vote and continue to support the rebels, known as contras.

"It will be very difficult for the miracle to happen that President Reagan would be willing to become a man of peace," Ortega said.

The somber tone was reflected in the scarcity of Sandinista celebration elsewhere in Managua. Moments after the House vote results were announced last night, Javier Reyes, a top commentator for the government's Radio Sandino, cautioned listeners: "This is only a setback for the Reagan administration. The war continues. There should be no rejoicing in Managua."

"We won't let down our guard," Ortega said. "As long as the war goes on, all Nicaraguans must remain massively, permanently mobilized to defend our revolution by every means . . . and to complete the total defeat of the mercenary forces," a standard Sandinista term for the contras.

"The war will only come to an end when the United States accepts a cease-fire in Nicaragua and renounces its policy of force and the possibility of using its military might to invade Nicaragua," he added.

The Sandinista president said his government will continue cease-fire negotiations with contra political leaders to set conditions for them to lay down their arms and return to civilian life in Nicaragua, or go into exile in foreign countries. A second round of direct cease-fire negotiations is scheduled for Feb. 10-12 in Guatemala. The contras have presented a proposal linking a cease-fire to sweeping political reforms in Nicaragua.

Congressional Democrats in Washington have said they may seek to approve an alternative package of humanitarian aid for the contras in coming weeks.

Ortega asserted that the only contra aid allowed under the regional peace plan, which was signed Aug. 7 by the presidents of Nicaragua, Honduras, El Salvador, Guatemala and Costa Rica, would come after a cease-fire is reached and would be for the purpose of resettling contra fighters who accept a government amnesty.

It could not be learned today how Ortega decided on his speech and comments, which he delivered dressed casually in a cotton cardigan, from sketchy notes. In the past, such statements came after closed meetings of the nine top comandantes who lead the ruling Sandinista front.

Ortega reserved some of his sharpest words for the opposition parties. "They must understand that as long as the government is fighting the contras, we can't make headway in a peace process.

"The two are incompatible. War negates peace," Ortega said.

He demanded that opposition politicians publicly reject the Reagan administration's "interventionist policies" and break any links to the contras. Some parties have called for a three-way peace dialogue to include the government, the opposition and the contras. Several opposition leaders were arrested briefly in January after returning from a meeting in Guatemala where they discussed the idea with contra political leaders.

As Ortega was speaking, representatives of 14 opposition parties marched to the National Assembly to present a new proposal for 17 constitutional changes intended to clarify the separation between the state, the Army and the Sandinista front.

The opposition parties asked the president to help them overcome a procedural technicality and introduce the reform proposal during the current legislative session.

In return for the president's assistance, the 14 parties, which represent all but a small fraction of the opposition, said they would return to a national political dialogue started last year under the Central American peace accord.

One leading opposition politician, Christian Democrat Agustin Jarquin, welcomed the U.S. House vote. The government "has no more excuses" not to allow broader democracy in Nicaragua, Jarquin said.

Ortega charged that El Salvador and Honduras continue to allow their territories to be used for contra operations, though he refrained from providing details. The peace accord calls for an end to all foreign support for rebel groups in Central America.

In his warmest reference to the House decision, he said it was "a vote of hope" that "should contribute to respect for the regional peace accord."