Eastern Airlines' offer of a 32 percent raise to avert a strike by its 13,500 machinists is "final," Eastern President Frank Borman said yesterday, but union leaders told their rank and file to reject the company proposal as inadequate.

Bargaining almost nonstop for six days, representatives for Eastern and the International Association of Machinists hammered out a 2 1/2-year pact that will be voted on Friday by the airline's mechanics, baggage crews and ground personnel.

Although District 100 president Charles Bryan backed off calling the strike that the union had threatened for 12:01 a.m. EST yesterday if its demands were not met, he said he was angry that Eastern's offer did not include retroactive pay hikes for 1982, when IAM members worked without a contract.

"We will vigorously recommend to our membership that they turn down this contract," said Bryan. "I think they will."

But Borman said that the 32-percent raise by November, 1984, was "Eastern's final offer. If the union membership rejects it, there will be a strike, and we will begin the difficult task of restructuring the airline."

Borman said the airline can't come up with the $30 million it would cost to fund the retroactive pay boost.