Trump administration officials, seeking to weaken Democrats’ case for impeachment, disputed on Thursday some of the details in the House Intelligence Committee’s report about calls between President Trump’s personal lawyer Rudolph W. Giuliani and White House aides.

As part of its portrait of Mr. Trump’s campaign of pressure on Ukraine, the committee’s report released this week listed several calls between Mr. Giuliani and White House phone numbers, including one “associated with” the White House’s Office of Management and Budget, cited in the report simply as “O.M.B. number.”

Such calls suggested contact between Mr. Giuliani and key officials at significant moments during Mr. Trump’s dealings with Ukraine. The budget office was involved in the administration’s freeze on $391 million in security aid for Ukraine, a key lever in the president’s pressure campaign.

But the phone number is a generic White House switchboard number, “(202) 395-0000,” people familiar with the phone records said, making it difficult to tell whose desk it came from. While government directories list it as associated with the budget office, they also show the number as associated with offices in other parts of the White House, including the upper floors of the West Wing and the National Security Council.