The United States will fly mock bombing runs over Honduras and practice quarantine maneuvers at sea in the forthcoming air and naval exercises off Central America, defense officials said yesterday.

They emphasized that the military plans now being refined do not call for direct confrontations with Nicaragua or for stopping foreign ships. Instead, the officials said, the idea is to display warning signs to Marxist forces and to demonstrate U.S. support for government troops in El Salvador.

Military planners yesterday were studying the best way to demonstrate U.S. ability to support friendly ground troops with warplanes based on carriers. If the plans go forward as expected, Navy A6 light bombers will fly practice runs over Honduras once U.S. troops arrive.

But before this can be done, officials said, elaborate communications gear and other equipment needed to coordinate air and sea exercises must be put on the ground in Honduras. This preparation will take several weeks, meaning the troop-support missions probably will not be flown until September or later.

The plans for practicing quarantine are further along, officials said, mostly because the maneuvers are less complicated than combined air and ground exercises involving the Army, Navy, Marines and Honduran forces. The exercises are expected to last about six months.

The Joint Chiefs of Staff's operational plan, which planners are filling in by designating forces to carry it out, calls for "exercising evolutions" that might be required off the east and west coasts of Central America, including "quarantine, blockade and interdiction of shipping." The plan orders drills, not the real thing, officials emphasize.

"People that are going down on these maneuvers are not sent down to fight," Defense Secretary Caspar W. Weinberger said recently. "They're not down there to engage in war or anything of that kind."

"It's a confidence-builder for the Hondurans," another defense official said yesterday of the extensive maneuvers in the works. But officials conceded that practicing quarantine maneuvers is designed in part to signal Warsaw Pact nations and Cuba that sending war supplies to Nicaragua could get dangerous.

A quarantine differs from a blockade in that only ships of certain nations are stopped, searched and turned back. A blockade usually amounts to warning all ships to keep out of specified areas or risk being sunk. Navy officials said that if a ship refuses to stop and be searched in a quarantine, the objective usually is to disable it, not sink it.

But the rules of engagement change with every situation. Defense officials said there is no sign that President Reagan is about to impose a quarantine off Nicaragua. The required ships are not yet in position anyway, they added.

The objective of a quarantine would be to reduce the shipment by sea of war supplies to Nicaragua, which supplies the anti-government forces in El Salvador. State Department spokesman John Hughes said yesterday that "We believe that significant amounts of ammunition, explosives and logistical supplies continue to arrive from Nicaragua by air, sea and land."

The department's statement came after published reports that war supplies from Nicaragua to the Salvadoran guerrillas had dwindled to a trickle.

Hughes, giving the administration's interpretation of the decrease, said: "With a stable force, previously well-supplied and having captured some arms in the field, the guerrillas have had less need of external supply of basic weapons since the early months of 1983. We have detected cyclical rises in deliveries prior to insurgent offensives, such as prior to the October, 1982, and January, 1983, offensives."

The aircraft carrier USS Ranger was about 100 miles off the Pacific coast of Nicaragua yesterday, officials said, while the carrier USS Coral Sea was steaming from the central Mediterranean to take a position off the country's east coast.

The battleship USS New Jersey is sailing from Southeast Asian waters to join the Ranger, which is expected to break from its position off Nicaragua's Pacific coast after several weeks of quarantine and other drills and head for the Persian Gulf.

Meanwhile, on Capitol Hill yesterday Republican protests derailed a Democratic effort to apply last week's House ban on U.S. support for the "secret war" in Nicaragua to a multimillion-dollar intelligence authorization bill.

Rep. Edward P. Boland (D-Mass.), chairman of the House Intelligence Committee, asked the Rules Committee to clear the 1984 intelligence authorization bill for quick floor action this week before the House leaves for summer recess. Before the day was out, aides said he abandoned the effort for the moment, because of GOP objections.

House Republican leaders complained that Boland's strategy would leave them with "no real chance to amend" the cutoff in covert CIA aid to anti-government guerrillas in Nicaragua that was adopted by the House last Thursday, 228 to 195.

"This is a disgraceful, unacceptable abuse of power," House Minority Leader Robert H. Michel (R-Ill.) charged of the Democratic attempt to add the cutoff to the bill providing spending authority for U.S. intelligence operations worldwide beginning Oct. 1.

Boland's proposal to the Rules Committee would have permitted only two amendments to the intelligence authorization bill concerning Nicaragua: one to incorporate what the House did last Thursday and one to strike the ban on covert aid.

Boland's plan would have limited debate to two hours in order to fit the measure into the busy House schedule for its final week before the summer recess, but House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) expressed concern that the controversy could bring about a prolonged floor fight.

O'Neill, who complained last week that lawmakers were not consulted in advance about the Central American military exercises, said he has been invited to a bipartisan leadership breakfast, "the first in months," at the State Department on Wednesday. O'Neill added that in his view the session is "a little late."