A controversial U.S.-Honduran joint military exercise intended in part to intimidate Nicaragua's revolutionary Sandinista government has been postponed for at least one month and may be scaled down considerably following a re-evaluation by Washington of the exercise, State Department officials report.

A key consideration in putting off the maneuvers, which were tentatively scheduled to begin Dec. 5, was the potential complication of President Reagan's recently announced visit to nearby Costa Rica on Dec. 4, these officials acknowledged yesterday.

Their comments also suggested that the administration is beginning to have second thoughts about the exercise itself. It comes at a time of controversy over U.S. military maneuvers in Central America when the Reagan administration is reported to have drawn up a plan of covert operations against Nicaragua's government, and just as the president undertakes a trip that would emphasize U.S. economic aid to the Caribbean basin.

"We looked at the political propriety of having [the maneuvers] at that time, and obviously the president's visit was a factor" in their scheduling, said one senior State Department official.

The exercises are also being rethought in the face of obvious confusion about them in Central America where Nicaragua says they are a cover for an invasion by antigovernment exiles based in Honduras near the Nicaraguan border. In the murky atmosphere of intrigue and subversion even the Honduran government seems unsure of what is happening when or why.

Just last Friday, Honduran National Radio announced that the maneuvers were definitely scheduled for Dec. 5. About two hours later the radio retracted the statement, said a mistake had been made and the exercises would not be held until after Jan. 1.

Much of the confusion springs from mixed signals from Washington that apparently result from an internal debate about just how far the Sandinistas can be pushed and for what purpose.

State Department officials say that final plans for the joint maneuvers, called Ahuas Tara, or Big Pine in the Miskito Indian language, were never definitively concluded.

"We preserve a pretty fair amount of flexibility on this right up to the last minute," said one.

Another senior official said, "The planning proceeds, really, at two levels," with some decisions made by personnel in the region and at the U.S. Armed Forces Southern Command in Panama, but "then all the plans have to be reviewed up here."

That process is still under way, he said, but added that "There was a tendency for planning decisions by some people in the region to be taken by some as final decisions."

As government officials and Western diplomats in Honduras described Ahuas Tara when interviewed last month, its outlines were well established, involving nationwide movement of Honduran troops with operational support, especially in transport and the use of sophisticated electronic equipment, from several hundred American soldiers.

The U.S. Army, Navy and Air Force would all be involved in the maneuvers which would center on the isolated Honduran garrison at Mocoron near the scene of frequent fighting between Sandinista troops and Nicaraguan rebels allegedly working out of Honduran base camps.

According to sources in the Honduran capital familiar with plans for the exercises, the original goal was a relatively modest one, described by the State Department as "cross-training to enhance the capabilities of the Honduran armed forces and an attempt to build Honduran confidence." But, as the planning developed, the scope of the exercises changed.

Honduran military men complained that the exercises were increasingly influenced by American "civilians" or intelligence agents who saw them as a tool to intimidate Sandinista Nicaragua -- "to rattle their cages" -- through a combination of visible force and manipulated information.

That the exercises would take place so close to the border, on a scale unprecedented in Honduran history and at a time when anti-Sandinista rebels allegedly receiving Honduran and U.S. support are inflicting serious casualties on the government's partisans made Managua's fearful reaction and public protests predictable.

A senior Defense Department official said in an interview last month, "We're not going to stop the exercise just because we've got a bunch of screaming Sandinistas over there."

But the scale of the operation was never agreed on, according to State Department officials, with some senior policy makers increasingly convinced that smaller maneuvers would be more worthwhile, with several international observers present to testify how benign the operations were.

Policy calculations are delicate and increasingly convoluted, with one State Department official suggesting yesterday that he was disappointed that the maneuvers would not be taking place around the time of Reagan's stop in Central America. If they did, he said, the Sandinistas would raise alarms about an invasion that would not happen, thus embarrassing themselves and diminishing their own credibility.

But as pressure on Nicaragua has visibly increased in recent weeks its protests so far have won it useful international sympathy. The United Nations' vote last week to give Nicaragua a seat on the Security Council was a conspicuous example of such sympathy and widely read as a setback for Washington's efforts to isolate Managua.