The Reagan administration stepped up its war of words against Nicaragua yesterday amid disclosures that the U.S. military is conducting seven separate exercises in neighboring Honduras, three of which began the day after the U.S. presidential election.

Michael I. Burch, the chief Pentagon spokesman, said in response to a question that the administration believes that Nicaragua has "designs" on Honduras and El Salvador, two U.S. allies in the region. He said that the Defense Department would "respond with whatever assistance was necessary" if Nicaragua attacks its neighbors. He said, however, that "there is no hard evidence that they plan to invade El Salvador and Honduras."

Nicaragua has denied any such intentions, accusing the United States of seeking a pretext to attack it and overthrow its leftist Sandinista government. Nicaraguan officials have said they are bolstering their armed forces to counter an indigenous rebel army of 10,000 to 15,000 men organized and financed by the CIA.

Burch said the United States has no plans to invade Nicaragua or to interfere with shipments of arms traveling to that Central American country. He criticized Nicaraguan leaders for "needlessly stirring up their own population" with alerts and predictions of imminent U.S. military action.

Burch's comments, reinforced by similar statements from White House and State Department officials, appeared to reflect an administration campaign to maintain pressure on the leftist government of Nicaragua while denying any military plans to attack that country. A White House official likened the situation following recent Soviet arms shipments to Nicaragua to the 1962 Cuban missile crisis, when Washington said it would not tolerate the shipment of nuclear missiles to Cuba.

Burch said current U.S. military exercises in neighboring Honduras and El Salvador are intended to "remind" the Nicaraguans "that perhaps they should not have any designs on their neighbors."

Pentagon officials denied before the election that they intended to accelerate the pace of military maneuvers in the region. Lt. Col. Dick Lake said yesterday, however, that there are now more exercises taking place than at any time since the major Granadero exercise ended last May, although the scale of the current exercises is smaller than Granadero.

Three of those exercises began last Wednesday, one day after the election, and a fourth began Thursday. Altogether they appear to involve more than 500 U.S. military personnel, although Pentagon officials said they could not provide precise numbers.

A Pentagon spokesman said there are now about 1,000 U.S. military personnel in Honduras, which is the same number the Pentagon provided before the exercises began.

The Pentagon did not announce any of the exercises until questioned about them, keeping silent at the recommendation of the U.S. Southern Command in Panama, a spokesman said. Several of the exercises were increased in size, again at the direction of the Southern Command, from what officials in Washington had said they would be two weeks ago.

U.S. exercises in Honduras have been controversial because they have lasted far longer than most maneuvers, suggesting to administration critics that the Pentagon is planning a long-term presence in that country and is actively assisting Nicaraguan rebels and the Salvadoran government in their separate civil wars. Pentagon officials have said they have no current plans for a permanent presence in Honduras.

According to Pentagon spokesman Lake, military personnel on maneuvers in Honduras now include:

* A company of about 120 engineers from Fort Bragg, N.C., who are building roads at Palmerola, where U.S. forces established a headquarters when they began large-scale exercises more than a year ago. Burch said the engineers also are "resurfacing and building dirt airstrips."

Democrats in Congress have criticized the Pentagon for allowing military construction, which normally must be approved by Congress in a separate budget, under the cover of military exercises. The Pentagon has said that the value of any facilities that are built is incidental to the training value to its engineers.

The engineering exercise is scheduled to last from Nov. 7 through Nov. 20.

* A company of 150 to 180 infantry troops from Fort Hood, Tex., conducting patrolling exercises in the vicinity of Palmerola. That exercise also will last from Nov. 7 through Nov. 20, Lake said.

* A medical clearing company from Fort Stewart, Ga., that would conduct triage during a war and is training at the U.S.-built and -operated hospital at Palmerola. That exercise also will last from Nov. 7 through Nov. 20.

* A contingent of about a dozen people providing "command and control" from ports in El Salvador and Honduras of a naval exercise called King's Guard, which began Nov. 8 and is to last through Nov. 19. A U.S. ship was scheduled to participate in the exercise with the local navies in the Gulf of Fonseca, which also borders Nicaragua.

* An Air Force exercise involving A37 attack planes from the Pennsylvania Air National Guard and O2A observation planes from Howard Air Force Base in Panama. That exercise, lasting from Oct. 28 through Nov. 17, will be based at airfields in Palmerola; La Mesa, near the Guatemalan border, and San Lorenzo, near the Nicaraguan border along the Gulf of Fonseca.

* Special Forces from Fort Bragg and Fort Gulick, Panama, conducting "counterinsurgency" exercises with Honduran troops. Lake said that he could not provide exact numbers or locations for the maneuver but said it is very small.

* Army preventive medicine teams who have been deployed for two-week tours at the hospital at Palmerola since late September and will continue this through the end of the year. The teams consist of about a dozen soldiers each, Lake said.

In addition, there are military personnel who are not considered to be on exercises in Honduras operating a radar station, the hospital, a training camp and other facilities and flying military intelligence missions, Lake said.

Burch said he would not quarrel with reports that three Soviet ships are approaching Nicaragua and are expected in port within a few days. Several officials with access to intelligence information said they do not believe that the ships contain military equipment, but Burch said he does not know whether they do.

The arrival of the arms-carrying Soviet ship Bakuriani last week triggered a flurry of hostile rhetoric between the United States and Nicaragua after administration officials said they believed that the ship was carrying Migs. No Migs were unloaded, but officials said yesterday that other dangerous equipment was delivered.

Some analysts continue to believe that Migs are aboard the Bakuriani, which left the Nicaraguan port of Corinto and is now heading south in the Pacific, officials said. The analysts do not believe that the ship's entire cargo was unloaded in Corinto.