"The State Department today ordered the departure from Monrovia of all eligible family members not employed by post in the coming days," Xinhua quoted department spokesperson Marie Harf as saying on Thursday.
"Washington is focusing its efforts on helping US citizens in the country as well as the Liberian government, international and local health organisations to deal with the unprecedented Ebola outbreak," Harf said.
Meanwhile, additional disease specialists, including 12 disease prevention specialists from the US Center for Disease Control and Prevention and a 13-member Disaster Assistance Response Team, were sent to Liberia.
The State Department also warned US nationals not to travel to Liberia.
According to the World Health Organisation (WHO), the Ebola outbreak since March has struck 1,711 people and has killed 932 in Guinea, Liberia, Nigeria and Sierra Leone.
The virus is spread through direct contact with the bodily fluids of those infected.
Liberia and Sierra Leone account for more than 60 percent of the deaths.