WASHINGTON - A Cuban exile leader convicted of counterfeiting, produced evidence today to show that the Government had known of his plan to undermine Cuba's currency but had not disapproved.

In a plea for suspension of a one-year prison sentence; Mario Garcia Kohly, president of a group called the Cuban Government in Exile, told of a cloak - and - dagger tangle, in which he said the Pentagon and the Joint Chiefs of Staff seemed to encourage 'his scheme' - and then stood by, as he was arrested and tried.

A motion for a suspended sentence was filed yesterday with the United States District Court in New York, where Mr. Kohly was convicted last July, and with the Justice Department.

The papers included an affidavit by a retired army colonel who talked with Mr. Kohly at the request of a Pentagon official, and a letter from an Army general who had discussed the scheme with Gen Maxwell D. Taylor, then Chairman of the Joint Chiefs of Staff, and a letter from former Vice President Richard M Nixon. Mr. Kohly, according to his testimony at trial, had been put in touch with the Central Intelligence Agency by Mr: Nixon.

Col. Warren H. Hoover, retired, said in his affidavit that William McCormick, a civilian employer in the Pentagon, had asked him to speak with Mr. Kohly in August, 1981, about the Cuban's plan to print counterfeit 10-peso notes. These would be used to purchase arms in Cuba for rebels and to weaken the Cuban economy.

At Mr. Kohly's request, the affidavit went on, Colonel Hoover discussed the plan with General Taylor and an aide, and a "gentleman in civilian clothes whose name and office I do not remember."

Colonel Hoover said he had recommended to General Taylor that the Government support the plan. He said Mr. Kohly had not been asking for financial support, but only that the Government take a "hands off" attitude.

The colonel said he received a telephone call from the Assistant United States Attorney Who was handling the case in New York.

He said he had told the caller that he would testify for Mr. Kohly because "if a criminal act had been committed, the United States Government was it least negligent in failing to so advise him." He said he had not been called to testify by either side.

One letter was from Brig. Gen. Julian J. Ewell, an aide to General Taylor in 1961. It said that General Taylor had been dubious of the plan because he did not think Mr. Kohly had strong backing among the Cuban people

General Ewell said the matter was referred to "appropriate persons" but that no one in General Taylor's office had spoken to Mr. Kohly again about it.

Mr. Kohly had testified at his trial that he met Mr. Nixon on a golf course and had outlined a plan to retake Cuba.

In his letter, Mr. Nixon said he had no knowledge of the particular circumstances, but he asked for favorable consideration of the plea for a suspended sentence.

He said the United States policy toward Premier Fidel Castro could have led Mr. Kohly to deliver honestly, though mistakenly, that he had Government approval.

At his trial the 63-year-old Cuban said that as head of the Cuban Government in Exile, he thought he was legally authorized to print Cuban currency in the United States.

A jury found Mr. Kohly guilty of violating a Federal law against counterfeiting the currency any foreign nation with which the United States is not at war.

The motion will be argued tomorrow.