Fourteen people have now died since the outbreak began in western Uganda three weeks ago, he said in a broadcast.
There have been no confirmed cases of the infection spreading in Kampala.
Ebola, one of the most virulent diseases in the world, is spread by close personal contact and can kill up to 90% of those who become infected.
Mr Museveni said health officials were trying to trace everyone who had had contact with victims so that they could be quarantined.
People should avoid shaking hands, kissing or having sex to prevent the disease from spreading, he added.
Mr Museveni said relatives and friends should not bury anyone who is suspected to have died of Ebola.
"Instead call health workers because they know how to do it," he said.