The Carter administration is moving to establish a multinational Caribbean seagoing patrol force as part of its effort to show resolve in the face of Cuban and Soviet aggressiveness in the Western Hemisphere, government officials said yesterday.

They added that the administration, as another part of its response to Soviet troops in Cuba and Cuban military adventurism in the Caribbean, is considering resuming sales of military equipment, but not modern weapons, to anti-Castro governments in Central America.

The idea of the Caribbean patrol force, Pentagon and State Department officials said, is to combat Cuban infiltration into island nations there. Under the proposal, the United States, Britain and Canada would provide coast-guard-type training in Barbados and possibly sell patrol boats to that country and others.

However, one government official laughed at calling the proposed force "a Caribbean navy" stressing that it would hardly start out as anything awesome. Another official referred to the idea as part of "the optics" of manifestion of Carter administration resolve in the Caribbean.

But in describing the longer range possibilities, one general on the administration's special task force considering responses to Caribbean problems said a coordinated coastal patrol force manned by nations friendly to the United States could do a lot of combat infiltration, gun-running and drug trafficking.

As it is now, the general said, many of Cuba's small neighbors in the Caribbean "can't protect their own coastlines," making them easy targets for such intrusions.

Barbados is taking the lead in forming a coast guard. The government there has in hand a British study of its coastal defense needs. The Carter administration is trying to get that plan implemented, with the help of Britain and Canada.

Barbados, an English speaking republic, recently was declared eligible for U.S. military assistance.

Although the administration would like to see a coordinated patrol force that also would include St. Lucia and St. Vincent, State Department officials expect that those eastern Caribbean island nations will decide to act independently.

On the western side of the Caribbean basin, administration officials see opportunities for stregthening relations by resuming sales of military equipment ranging from new engines for DC3 transport planes, to jeeps to uniforms.

President Carter has pledged repeatedly to reduce the export of American arms. Also, many State Department officials have warned that sending American weapons into the Caribbean basin would alienate people there, thus playing into the hands of Cuban President Fidel Castro.

Philip C. Habib, formerly under secretary for political affairs to Secretary to State Cyrus R. Vance, stressed in a recent report commissioned by his former boss that the best medicine for ailing Caribbean nations would be economic, not military, aid.

In his television report on the Soviet combat brigade in Cuba, Carter pledged that part of his response would be increased "economic assistance to alleviate the unmet economic and human needs in the Caribbean region. . . ."

Administration officials said yesterday that they are well aware of the dangers of selling advanced weapons to Caribbean basin countries and will keep the exports in "the nonlethal" category.

However, critics are expected to view any stepped-up exports of U.S. military equipment to Central America as a prelude to arms sales.

The administration Caribbean task force, representing the White House, State Department and Pentagon, is reviewing the military needs of El Salvador, Guatemala and Honduras with an eye to selling them "nonlethal" equipment.

As part of the same review, administration officials are assessing ways to provide additional military training to officers of friendly nations in the Caribbean basin.

Air Force Lt. Gen. John S. Pustay, who represents the Joint Chiefs of Staff in many of the Caribbean taskforce meetings, said in an interview yesterday that the military threat from the Soviet brigade in Cuba 'is virtually zilch."

The worrisome threat in the Caribbean, he said, stems from the paramilitary operations of Cuban forces, with their "covert assistance" to the overthrow of President Anastasio Somoza of Nicaragua a recent example.

The Joint Chiefs welcome President Carter's decision to conduct show-the-flag exercises in the Caribbean in an attempt to demonstrate support to friendly governments and resolve to hostile ones.

Pustay said the immediate challienge is to "frustrate the momentum" of Cuba's "aggressive strategy."