The boxing legend died at the age of 74 last Friday in Phoenix. World leaders including Turkish President Recep Tayyip Erdoğan and King Abdullah of Jordan will be attending the memorial service in Ali’s hometown, Louisville, Kentucky.
Obama has been scheduled to attend his daughter Malia’s high school graduation instead.
“They will be attending Malia’s high school graduation ceremony in Washington, DC,” said spokeswoman Jen Friedman.
Instead, a close aide “will read a letter from the president and the first lady as part of Friday’s service in Louisville.”
Bob Gunnell, a spokesman for the Ali family, said Mr Obama and Ali’s widow Lonnie had spoken by telephone.