First ask yourself this question. This will help you understand the potential for injury. You probably didn't put all your weight on your pet. Also, most cats will vocalize as soon as they realize what's happening.
If you're not able to tell exactly what part of your cat you stepped on, at least try to figure out which part you know you didn’t step on.
Approach your cat slowly, give it some time to calm down, and start petting it gently. This will give you a chance to find any sensitive areas or injuries.
If your cat has any kind of fracture, sprain, or significant internal injury you’ll know very quickly. These injuries will cause changes in your cat’s behavior including changes in the way it moves.
If you’re seeing any changes in your cat’s behavior or a sensitivity to a specific area, then it’s time to contact your veterinarian.
You should be relieved to know that your cat will forgive you for the accident. It might, however, be a little more careful around you. You can make it up to your cat with extra pets, playtime, and by just having fun with it!