The travel ban was extended Tuesday to include citizens from Burkina Faso, Mali, Niger, the Palestinian Authority, South Sudan, and Syria, according to the White House.
South Sudan's government has grounded four aircraft registered under the United Nations mission there, alleging that they were used for illegal surveillance and smuggling.
U.N. experts warn that the treason trial of South Sudan's suspended vice president is further eroding a 2018 peace agreement he signed with President Salva Kiir.
The United States on Thursday warned it could cut foreign aid to South Sudan, accusing the government of imposing exorbitant fees on humanitarian groups and obstructing their operations.