White House press secretary Jay Carney told reporters aboard Air Force One the president spoke with Harris' daughter, Wilma Parsons, by phone after learning the owner of Ann's Restaurant had died.
"So the president expressed his sorrow and his condolences at the very sad event," Carney said. "He was honored to meet her this morning and passed on his feelings that the whole family is in his thoughts and prayers today.
Carney said it was his understanding, based on press reports, that she had not been well and died of a heart attack.
The Akron Beacon Journal reported Harris, 70, was taken by ambulance to Akron General Medical Center after complaining of fatigue and a tingling feeling following Obama's visit. She died at the hospital about 11:15 a.m.
"You know it's great," Harris had said after Obama left her restaurant.
She hadn't known Obama intended to stop by during his campaign swing through Ohio and Pennsylvania until earlier in the morning.
"He treated us like one of the brothers," she said. "He hugged all of us and ... got his picture taken with all of us."
Frankie Adkins of Tulsa, Okla., said her sister had "loved Obama."
"It was just so fast," Adkins said of Harris' passing.
"Ann is really the matriarch of the whole thing. She was the backbone."