Flight 201, an Airbus A350, from Johannesburg was initially set to arrive at Hartsfield-Jackson Atlanta International Airport on Sunday but was instead routed to Boston's Logan International Airport, Delta said.
The diversion "has to do with technical specifications of our A350 aircraft and the payload of this particular flight," the company said in an email.
"This can happen on ultra-long-haul flights when optimal operating conditions can't be met," it said.
The Federal Aviation Administration told Reuters it would investigate the situation.
The flight, which was initially scheduled to land in Atlanta at 8:15 EST (1215 GMT), was rescheduled to land at in Boston at 9:27 a.m. before departing for Atlanta at 10:40 a.m., it said.
The company did not cite the newly discovered Omicron variant of the coronavirus, which has been detected in South Africa, as a reason for the temporary diversion.
More than a dozen passengers on a flight from Johannesburg to Schiphol that landed Friday tested positive https://www.reuters.com/world/europe/dutch-set-announce-findings-omicron-cases-among-safrica-travellers-2021-11-28 for the new variant, Dutch authorities said on Sunday.
(Reporting by Peter Szekely in New York and David Shepardson in Washington; Editing by Heather Timmons and Mark Porter)