The United States charged yesterday that the Nicaraguan government has accused 14 Nicaraguan employes of the U.S. Embassy in Managua of working for the Central Intelligence Agency and has subjected them to "abusive interrogation" and "psychological abuse."

The State Department formally protested to the Nicaraguan Embassy here yesterday about the incidents.

Department spokesman Charles Redman also issued a statement describing what he termed "unacceptable harassment" of employes performing "the normal sort of support functions as foreign nationals in any U.S. embassy in the world."

In addition to the statement, department officials said privately that the incidents appear related to the Sandinista government's campaign to intimidate the populace and stifle dissent against its leftist policies.

The officials said it also seemed to be a retaliatory tactic against the United States for its support of counterrevolutionaries, known as contras, fighting the Sandinistas.

Redman said that between Nov. 2 and last Thursday the 14, who work as drivers or clerks, were summoned before Nicaraguan security authorities, in some cases through late-night visits, and "subjected to long periods of intense and often abusive interrogation, ranging from six to 13 hours . . . . "

"All have been subjected as well to psychological abuse by being forced to sit for extended periods of time in small windowless rooms, by being allowed to sit or speak only at the whim of the interrogator and by being forced to walk at all times with their heads down and eyes on the ground, accompanied by armed guards," Redman said. "All have been accused of working for the CIA, and all have been told they were 'prisoners,' " he added. "So far, all have been released, but with warnings that they will be under surveillance in the future.

"We reject any claims that these employes are engaged in espionage activities," he said. "We have strongly protested these efforts at intimidation to the Nicaraguan government and call on that government to cease them immediately."

In a message delivered last night to the U.S. Embassy in Managua, the Nicaraguan Foreign Ministry called the State Department protest "insolent" and said it appeared to be "a new provocation by the U.S. government." The message did not address the U.S. charges.

Redman also said conditions issued Monday by Nicaraguan President Daniel Ortega for signing a treaty to resolve Central American tensions "appear designed to make agreement difficult if not impossible." Ortega reportedly said his government will not subscribe to the draft treaty being drawn in the Contadora negotiating process until the contras end their insurgency. Redman said Sandinista refusals to engage in dialogue with the contras "are the real obstacle to peace."