In neighbouring Vietnam, 26 people have been admitted to a Hanoi hospital with a bacterial infection from diseased pigs, leading to two confirmed human deaths.
Twenty others were treated this year in southern Vietnam for the same illness.
Thursday's ban is also aimed at cutting down on pork products smuggled into the country, mostly from Vietnam.
Contraband pork raises "the possibility of infection among pigs in Cambodia and could block the development of family farms," said the public directive, which was ordered by Prime Minister Hun Sen.
Most small family farms in rural Cambodia have at least one pig, and pork is a key source of food, as well as an important commodity for often impoverished farmers.
The order does allow piglets to be imported for breeding or research purposes, as long as they receive approval from the agriculture ministry.
Cambodia has taken similar measures against poultry imports in the past in a bid to contain bird flu, which has hit hard the poultry industry in both Vietnam and Thailand.