WASHINGTON — A senior Pentagon official publicly apologized yesterday for criticizing lawyers who represent terrorism suspects detained at the American prison at Guantanamo Bay, Cuba, and for suggesting their firms be boycotted.

Charles “Cully” Stimson, deputy assistant secretary of defense for detainee affairs, said his criticism of the lawyers on a local radio program last week did not reflect his “core beliefs.”

“My comments left the impression that I question the integrity of those engaged in the zealous defense of detainees in Guantanamo,” Mr. Stimson said in a letter to the editor published in the Washington Post.

Mr. Stimson drew outrage from the legal community — and a disavowal from the Defense Department — after he said he found it shocking that lawyers at many of the nation’s top law firms represent detainees held at the American military prison in Cuba.

He suggested some were being untruthful about doing the work free of charge and said companies might want to consider taking their business to other firms that do not represent suspected terrorists.

“I believe firmly that a foundational principle of our legal system is that the system works best when both sides are represented by competent legal counsel,” Mr. Stimson said in the letter to the Post, adding that he supports pro bono work.