Nicaragua is fully prepared to defend itself without outside aid against any U.S. military intervention there, Nicaraguan officials told the Kissinger commission on Central America last week. The Nicaraguans said yesterday that they are prepared to mobilize an army of 500,000 to face any invasion.

Henry A. Kissinger, head of President Reagan's new Bipartisan Commission on Central America, and three commission members met with Nicaraguan Ambassador Antonio Jarquin on Thursday, Jarquin said yesterday.

They also met Thursday at the State Department with the ambassadors of El Salvador and Honduras and with the charges d'affaires of Guatemala and Costa Rica, according to diplomats from those countries.

One result of the meetings is that all 12 commission members and their eight adviser members of Congress will visit the five countries, including Nicaragua, in the next few weeks as part of what Kissinger said was his effort to educate himself and his group on the problems of the region, Jarquin told reporters.

One diplomat from the area said Kissinger also planned to visit the four countries of the Contadora group--Venezuela, Mexico, Colombia and Panama--that are trying to negotiate political solutions to the region's problems.

Jarquin said Kissinger "told me he is not going to be engaged in the issue of negotiations or in short-term problems" of Central America, but rather will seek longer term solutions to conditions underlying the military conflicts in the area.

Other Nicaraguan officials said Kissinger went out of his way to insist that he will not mediate or negotiate and that there is no "back channel" of access to the Reagan administration through him.

Instead, the officials said, Kissinger praised the efforts of presidential envoy Richard B. Stone to foster talks between the government and rebels in El Salvador.

In response, Jarquin said, he told Kissinger that the Reagan administration continued to display "a blockade attitude" toward Nicaragua and responded to Nicaragua's six-point negotiating proposal of July 19 with a naval show of force off Nicaragua's coast.

The first 150 of an expected 4,000 U.S. troops landed yesterday in Honduras to begin several months of war games in the region.

"We have been preparing for four years to defend ourselves," Jarquin said at the news conference. "We are not expecting military aid from any other country if the United States decides to come in . . . but politically, thousands of Latin Americans would be heard from."

Saul Arana, head of the North American department in Nicaragua's ministry of foreign affairs, said after the news conference that the country could mobilize 500,000 people "in a moment" if necessary.

"That is what you will see in the next few weeks if this thing continues to worsen," he said. Arana pledged that the Nicaraguans "will not give the U.S. troops any excuse to use as a provocation" to hostilities, but added that accidents happen and that tensions are high. "It's a difficult moment, I would say a crucial time," he said.

The Kissinger commission members will be sworn in Wednesday and then have their first official meeting with Peter MacPherson, head of the Agency for International Development, and with Langhorne Motley, assistant secretary of state for Latin American affairs.

President Reagan and Secretary of State George P. Shultz gave a smiling sendoff yesterday to their new ambassador to El Salvador, Thomas R. Pickering.

State Department spokesman John Hughes said the meeting served as a get-acquainted session and "to underscore that the president is concerned with and involved in the situation in El Salvador."

In a related development, French foreign minister Claude Cheysson, reporting on his Central American trip in a radio interview, said Cuban President Fidel Castro "realizes there is a danger of the situation becoming unstuck in Central America."

He praised Castro for "sincerity and pursuit of truth," and said nations in the area should be allowed to settle their tensions among themselves. "Those countries know the situation better than the United States," he said.