A federal judge ruled yesterday that decisions by baseball commissioner Bowie Kuhn cannot be appealed to the courts.

Judge Frank J. McGar of Chicago found that a no-suit covenant in baseball's constitution is "valid and enforceable" and that Oakland A's owner Charles O. Finley had violated the provision by suing Kuhn.

Finley filed suit last summer after Kuhn nullified the $3.5 million sale of three Oakland players. McGarr ruled in March that Kuhn had thea authority to cancel the sales.

"Can't sue huh?" Finley said of yesterday's decision. "Well, I did." His lawyer, Neil Papiano, said McGarr's decision would be appealed.

Irvin B. Nathan, one of Kuhn's attorneys in the Finley case, called McGarr's decision "a very strong precedent . . . that will have great impact in future decisions. This has established the authority of the commissioner to make decisions without the constant threat of legal review."

The judicial-waiver clause, ratified by baseball club owners, is intended to free the commissioner to make impartial, third-party judgments "in the best interest of baseball" without being subject to costly suits.

Finley, who objected to the covenant when the clubs reaffirmed it in 1964, "knowingly accepted and signed the agreement containing it," McGarr wrote.

"The agreement is clear and the results clearly intended," he continued. "The court has several times questioned the wisdom of this no-appeal, no-litigation agreement, but its wisdom is not an issue before the court."

Kuhn's lawyers, in pretrial motions, sought to have Finley's suit dismissed because of the no-suit clause, but McGarr said he wanted to hear the merits of the case before deciding on the validity of the covenant. He noted in yesterday's decision that "mental reservations" about the legality of such agreements often exist in signators of such pacts.

After Kuhn won the case, his attorneys sought another ruling on the provision. Kuhn's lawyers and those for the Boston Red Sox also requested McGarr to order Finley to pay attorneys' fees and court costs. The Red Sox complained that Finley had caused them heavy legal fees by violating the no-suit covenant.

The Boston club was a codefendant because it had agreed to pay $1 million each for Joe Rudi and Rollie Fingers, but later embraced Kuhn's decision and backed off from the deal.

McGarr did not order Finley to pay costs and fees, noting that he had a right to have the legal validity of the covenant tested and, therefore, had not acted with "malicious or bad faith disregard of his contract obligations."