A spokesman for Secretary of Interior James G. Watt said yesterday that Watt never saw the letter one of his aides sent to an energy company executive that led to the firing of the company's Washington lobbyist.

Timothy L. Donohoe was fired from his $30,000-a-year job with Enserch, a Dallas-based natural gas company, after writing Watt a letter questioning the secretary's statement quoted in a newspaper article that he divided the political world, not between Republicans and Democrats, but between "liberals and Americans."

Instead of replying to Donohoe, Stanley W. Hulett, an assistant to Watt and director of Interior's congressional liaison office, sent a copy of Donohoe's letter to William C. McCord, the chairman and chief executive officer of Enserch. Hulett wrote that "the secretary is, frankly, surprised at Mr. Donohoe's representation in the attached letter." Enserch then fired Donohoe.

Douglas Baldwin, Interior's director of public affairs, said yesterday that Watt "was not involved in that Hulett's letter. He learned about it when he read it in the paper today." Later, Baldwin added that Watt had read Donohoe's letter and was "surprised" at its contents, but Baldwin insisted that Watt gave "no instruction to anyone on the staff to pursue it further."

Hulett continued to refuse telephone calls, but Baldwin said that answering the letter "was within the scope" of Hulett's office. Asked why Hulett had written to the corporation president, with a copy to the head of the American Petroleum Institute, rather than to Donohoe, Baldwin said: "Often a letter of praise is sent to a supervisor so the subordinate gets credit."

Asked if that was the intent in this case, he said, "No."

Meantime, Candice J. Shy, the head of Enserch's Washington office, said the "bad judgment" for which Donohoe was fired was his reference to himself as an energy company lobbyist and the fact that the stationery on which he wrote, while not having the company name, did have its Washington address and phone number.