MANAGUA, NICARAGUA, OCT. 11 -- A crowd of conservative Nicaraguans waving American flags cheered a speech today by former ambassador to the United Nations Jeane Kirkpatrick as a handful of Americans protested her visit.

Kirkpatrick, now a private citizen, was on a 24-hour whirl through Managua. She arrived in a U.S. Air Force plane, sent by President Reagan to give a Columbus Day address.

U.S. diplomats said her visit was part of a campaign by the embassy to show support for opposition groups by taking advantage of new freedom here since the signing Aug. 7 of a regional peace accord.

The invitation-only fete was held at the palatial Casa Grande, a former official residence of the U.S. ambassador that has been used only for ceremonial occasions since the 1979 revolution because it was associated with U.S. backing for the Somoza dynasty.

About 800 Nicaraguans from groups opposing the Sandinistas took in Kirkpatrick's rousing but largely philosophical half-hour speech like water in the desert.

"Perhaps the Sandinistas could win a free election," Kirkpatrick said in Spanish. "NO!" the audience booed.

Applause then thundered when she noted: "Some 15,000 Nicaraguans have taken up arms to fight for the liberty they thought they'd won in 1979," a reference to U.S.-backed rebels, known as contras.

While calling for new elections in Nicaragua, she repeatedly refused to rule out the possibility that the leftist Sandinista government might comply with the peace accords by a Nov. 7 deadline.

Nicaraguans who had taken up dozens of small American flags planted as garden decorations, ignored the rolling camera of Managua's official television and waved them enthusiatically during the speech.

While Kirkpatrick talked, six American protesters suddenly stood up in front and unfurled a banner that read, "Support the Central American Presidents' Peace Accord," referring to the Aug. 7 pact. One shouted, "Viva Free Nicaragua!"

"As U.S. residents in Nicaragua, we want our government to stop its aggression," said Mary Delaney, speaking for an organization of pro-Sandinista Americans living in Nicaragua. The Reagan administration is seeking $270 million in renewed contra aid.

After the speech, the protesters were chased and jeered by Nicaraguans yelling, "Go away, Yankee communists!" The Americans left the embassy grounds.

A U.S. diplomat said the demonstrators were not invited to the speech but as U.S. citizens were within their rights to attend.

Yesterday, Kirkpatrick had a "cordial" interview with two Sandinista dailies but did not meet with any government officials, a U.S. envoy said.