If your female is spayed, the males should not be interested in mating with her. If they seem interested, you need to evaluate whether they are just humping as part of play, bullying or if they are really trying to mate. In any case, this form of interaction should be discouraged. If they are truly trying to mate, there are chances your female may be emitting some odor that resembles a dog in heat. This can happen at times if your female has a urinary tract infection, or if her glands under the tail are infected. Sometimes, although rare, even though a female dog is spayed, the vet doing the surgery may leave some ovarian tissue behind and this may cause her to still go in heat. The best way is to keep them separated until you can find out why they are so interested in her.