The latest travel update comes after the United States and the United Kingdom warned on Sunday of a possible terrorist attack in the capital, Abuja, especially aimed at government buildings, places of worship and schools, among other targets.
"Non-Emergency" personnel include families and staff who are not needed to directly support the ambassador and charge 'd affaire or support security that protect the embassy.
"The U.S. Embassy Abuja continues to have limited ability to provide emergency assistance to U.S. citizens in Nigeria," the State Department said.
Nigeria's Department of State Services said the United States had previously issued similar warnings and urged citizens to remain alert.
Insecurity, which is rife across most Nigerian states, is a major issue among voters who will choose a new president next February.
