Delta, along with American and United Airlines, argue that Gulf carriers Emirates, Qatar and Etihad airlines are government-subsidized in violation of international Open Skies agreements.
The route cut by Delta comes as Qatar Airways prepares to launch flights from Doha to Atlanta starting June 1, 2016.
Delta launched its Atlanta-Dubai route in May 2007 with service five times weekly, and first increased to daily service in 2008. Delta in August said it would cut the Atlanta-Dubai flights from daily service to fewer days per week starting Oct. 1 due to "overcapacity" on U.S. routes to the Middle East by Gulf carriers.
Delta, American and United have asked the U.S. government to open consultations with Qatar and the United Arab Emirates over the issue of subsidies from those governments to the Gulf carriers.