Navy Secretary John F. Lehman Jr. said yesterday that he considered statements by an executive of a major defense contractor who supported cuts in President Reagan's arms program "a personal affront." The secretary said he supported his deputies for complaining to the executive's superiors, which led the company to dismiss Lawrence J. Korb.

Lehman said neither he nor his deputies asked the Raytheon Co. to fire Korb, a vice president of the firm and a former assistant secretary of defense. Raytheon is the nation's third-ranking arms maker and was competing for two major missile contracts at the time Korb was dismissed as vice president.

"Nobody asked for or expected Korb would be fired," Lehman said yesterday in a breakfast meeting with reporters. "I had every hope Raytheon would tell him to shut up and stop testifying against its principal customer."

The controversy was prompted by Korb's support in February of a report urging the military to reorder its priorities and accept a defense budget smaller than Reagan requested.

Lehman said Defense Department officials considered it "a personal affront . . . a so-called team member would join forces of the opposition. Gentlemen don't do that."

Although Lehman said he never ordered his deputies, Everett Pyatt and Melvyn R. Paisley, to contact Raytheon officials about Korb, "I certainly said things like, 'How the hell can Raytheon get away with going up, speaking out against the president's bill like that?' "

Lehman added, "I applaud the fact that my two secretaries and others complained to Raytheon about that kind of behavior."

Korb, who will soon become a dean at the University of Pittsburgh, said yesterday, "I didn't say anything in that February press conference that I had not said when I was a member of the administration. I said we ought not to take the easy way out."

Raytheon executives told Korb earlier that he would have to be replaced because of Navy objections, but that he could stay on until September, Korb said last week. Raytheon subsequently announced that Korb was a "special adviser" rather than a vice president.

Lehman stopped short of saying that his deputies threatened to take direct action against Raytheon because of Korb's comments, but said, "You don't have to get specific. It's understood you're unhappy."