"We have restricted non-essential travel to countries affected by Ebola," Exxon spokesman Patrick McGinn said in an email. The decision was made two weeks ago.
Exxon is exploring for oil in Liberia, one of the three countries severely hit by the disease. The others are Guinea and Sierra Leone.
"Safety, health and logistical issues related to Ebola will delay the planned late 2014 start of ExxonMobil's first exploration well offshore Liberia," McGinn added.
"Safety is our top priority. Travel restrictions into and within the country have severely limited our ability to progress plans for drilling."
But the company was not clear on whether the travel ban included its operations in Nigeria, which has seen about 20 confirmed Ebola cases but so far appears to have the disease under control.
It comes two days after the first case of Ebola was diagnosed inside the United States, of a man who traveled to the country from Liberia in September.
VIDEO: Ebola patient's Dallas hosts may be confined 3 weeks; officials talk to 100 people who may have been near him: http://t.co/Wln6GEh6PE— The Associated Press (@AP) October 3, 2014
The man is being treated in a hospital in Dallas, where the Exxon headquarters is located.
Texas health officials said they were monitoring 100 people who possibly had contact with the man for signs of the disease, and ordered four close family members to stay home.
The outbreak of the Ebola virus has killed more than 3,300 people.
Copyright Agence France-Presse, 2014