AFL-CIO President George Meany's prediction that postal workers will reject a proposed new contract drew anguished protests from postal union officials yesterday, along with a carefully worded dissent from Postmaster General William F. Bolger.

Bolger told reporters he is reasonably confident the contract will be ratified later this month. If it isn't, he said in a confirmation of earlier reports, the Postal Service will seek arbitration of the dispute instead of returning to the bargaining table.

This would reopen all issues thought to be settled in the tentative agreement negotiated July 21, including retention of the "no-layoff" clause that the unions wanted above all else.

Postal union leaders complained that Meany overlooked this point in criticizing the postal pact's provisions for a 19.5 percent pay increase over three years, which he said was not enough.

"Mr. Meany is dead wrong," said Emmet Andrews, president of the American Postal Worker Union, the largest of four unions representing more than 550,000 postal workers. "The money package gives our members more money than the previous contract while continuing the no-layoff clause, which was our principal objective in the negotiations."

If news reports of Meany's remarks were correct, "they constitute interference in the internal affairs of the unions," said James LaPenta, a negotiator for the Mailhandlers.

"I believe I know a little more about the contract than Mr. Meany," complained Joseph Vacca, president of the National Association of Letter Carriers.

AFL-CIO spokesman Albert J. Zack confirmed that the news accounts of Meany's comments were correct but said they were directed only at the money settlement. Postal union officials "have every right to disagree," he said.

The internal dispute was rare if not unprecedented because Meany makes it a practice not to comment on contracts negotiated by union affiliates. Meany made the remarks in the context of criticizing Carter administration efforts to keep down the costs of wage settlements - an effort marked by success thus far only in the case of the postal contract.

"We got whipsawed by the inflation fight," said one postal union source.

Returns are not expected from the ratification referendum until late this month, and Meany's criticism added to the uncertainty over the outcome. "I don't think it will have any great effect except to confuse people," said Vacca.

Bolger, in an appearance before the Washington Press Club, said his predictions of ratification were based on a "gut reaction."

An aide to Meany said his information was based on sources other than union officials who have been predicting ratification. The contract has been rejected in nonbinding votes by the national bargaining advisory committee to the APWU and by delegates to a national convention of the Letter Carriers.

A strike is possible but not certain if the contract is rejected. Two knowledgeable union sources said, however, that a strike is likely if the Postal Service pushes again to get rid of the "no layoffs" clause, which bars layoffs except by attrition.

While asserting that all issues would be reopened if the dispute went to official fact-finding and arbitration, as prescribed by postal labor laws when negotiations fail, Bolger stopped short of saying the Postal Service would push again to get rid of the controversial clause. A decision on that would not be made until after the vote, he said.