The 71-year-old pontiff made the decision on doctors' advice, the Vatican said, as a separate statement from his surgeon and personal doctor said a chest examination showed excellent progress in Leo's recovery.
The Pope had the lower lobe of his right lung removed in surgery on October 13 and was diagnosed with lung adenocarcinoma, the most common form of lung cancer.
The Pope's doctors said on Wednesday that further exams of the tissue removed in the operation had confirmed the cancer was localised and he would not require any further ongoing cancer treatment.
Leo had been due to travel on October 27 to Assisi, about 175km north of Rome, for a peace event with other religious leaders.
"To support his recovery following thoracic surgery last Tuesday, and in accordance with doctors' advice, Pope Leo XIV will be unable to attend," the Vatican statement said.
Leo was discharged from hospital on Saturday and is gradually resuming his normal duties.
On Wednesday, he returned to St Peter's Square for his weekly audience with pilgrims.
The Vatican has not said whether the Pope will be able to go ahead with a scheduled November 6-17 trip to Uruguay, Argentina and Peru.
