On Twitter Tuesday morning, President-elect Donald J. Trump was the media-bashing firebrand many of his supporters adore, denouncing The New York Times as a “failing” institution that covered him inaccurately — “and with a nasty tone!”

Eight hours later, after a lunchtime interview with editors and reporters for The Times — one that was briefly canceled, after Mr. Trump quarreled over the ground rules, then restored — the mood of the president-elect, it seemed, had mellowed.

“The Times is a great, great American jewel,” Mr. Trump declared as he prepared to leave the gathering in the newspaper’s 16th-floor boardroom, where portraits of former presidents adorn the walls.

“A world jewel,” added Mr. Trump, who was seated next to Arthur Sulzberger Jr., the paper’s publisher. “And I hope we can all get along.”