icaraguan head of state Daniel Ortega publicly confronted the United States in the U.N. Security Council today with charges of "aggressive and destabilizing acts" against his country and an offer to negotiate their differences alone or along with Cuba and El Salvador's guerrilla forces.

U.S. Ambassador Jeane Kirkpatrick replied that the Nicaraguans were displaying "paranoid" behavior by "accusing the United States of the kinds of political behavior of which Nicaragua is guilty--large-scale interventions to overthrow neighboring governments." She said Washington did not "close the door on negotiations," provided Nicaragua "is willing to address our concerns."

Each side presented a lengthy and by now oft-repeated catalogue, raid by raid and arms shipment by arms shipment, of the other's alleged offenses.

Ortega, whose government requested the meeting, did not attempt to refute Kirkpatrick's charge that Nicaragua is arming and masterminding the guerrilla movement trying to overthrow the U.S.-backed government in El Salvador. He said only that this has "never been proven," and that "the important thing is not to seek the causes" of the dispute, but to consider solutions.

Ortega said the five-point peace plan outlined last week by Secretary of State Alexander M. Haig Jr. "could be considered an encouraging element." He later told a press conference that Nicaragua is willing to negotiate immediately, unconditionally and either bilaterally or in company with the Cubans and Salvadoran leftists. Ortega said that both Havana and the Salvadoran rebels had asked him to make this commitment for them.

Although Nicaragua, Cuba and the Salvadoran guerrillas each have offered negotiations in the past, and Ortega last October delivered a Salvadoran proposal to the U.N. General Assembly, today's offer was believed to be the first time the three entities had expressed a desire to discuss the matter with the United States jointly.

But the Nicaraguan leader, wearing his military dress uniform, expressed serious doubts about American sincerity. He said negotiations would be without purpose unless Washington changes its attitude and declares publicly that it has no plan to intervene in Nicaragua, directly or covertly.

"A reply has to be given," he said. "A political negotiated settlement cannot be pursued while at the same time aggressive plans are being pursued. The door to peace will be open only when interventionist acts are stopped." Nicaragua has long charged U.S. complicity in backing rebels who want to overthrow the revolutionary government in Managua. In recent weeks, Managua has said it considers U.S. press reports that the Reagan administration has approved covert assistance for the rebels as confirmation of its charges.

Just as Ortega did not deny Nicaraguan aid to the Salvadoran guerrillas, Kirkpatrick, while denying that the United States is about to invade Nicaragua, made no attempt to refute the charge of covert destabilization efforts.

Kirkpatrick also said Washington is "somewhat skeptical when Nicaragua says it wants peace or better relations with the United States."

She charged that each time the Reagan administration has proposed negotiations, "Nicaragua responds by sending Daniel Ortega to deliver an attack on the United States."

Later, she said that in addition to the "strange" rhetorical response of Nicaragua to peaceful overtures, the ruling Sandinista National Liberation Front's "pattern of action" has demonstrated their aggressive intent.

"Nonetheless," she concluded, "if Nicaragua is willing to address our concerns on intervention, we are prepared to address their concerns. We do not close the door on negotiations. The choice is theirs."

Yesterday, Mexican Foreign Minister Jorge Castaneda was quoted as saying the United States and Nicaragua had officially asked to hold high-level bilateral talks in Managua to examine "all pending problems between them." Castaneda's office confirmed reports quoting the foreign minister as saying such talks probably would take place "very soon." Mexico's president, Jose Lopez Portillo, actively has sought to bring about negotiations in the Salvadoran situation.

Venezuela's Christian Democratic President Luis Herrera Campins, a supporter of Salvadoran junta leader Jose Napoleon Duarte, said Tuesday he would not close the door on support for a negotiated end to the fighting.

While unrelenting in his criticism of the United States, Ortega's speech today was far less vitriolic in tone that the one he gave to the General Assembly last October. He was even more conciliatory in his closed door addresses to the Latin American group and the nonaligned nations.

Western diplomats, comparing the two speeches, conceded that Kirkpatrick's words were somewhat harsher in tone. But they all stopped at the idea that today's public posturing would have any real impact on the prospects for negotiation.

"This is just blowing off steam," said the ambassador of a close American ally. "Nicaragua wanted to use this platform, and if it helps permit negotiations, well and good."