Yes horses do have several predators and one of those predators include us humans.
Yes you read that right humans are one of the predators of horses.
Other predators of horses are mountain lions, bears, coyotes and even Wolves.
When a horse senses it's in danger of being attacked or eaten then they will first flee the area if they can but if not they will resort to fighting back such as kicking, butting and even standing up on their rear legs to fight back the predator who is trying to attack them.