You can try gently pressing his head/shoulders down for a few seconds, when he is displaying unwanted behavior. It's something the head rabbit does to discipline other rabbits. Or you could try giving him a stuffed animal to take his hormonal frustrations out on. Just make sure it doesn't have loose threads or things that he could chew off and possibly ingest. Also keep an eye on him with it to make sure he isn't chewing it too much that he might ingest something dangerous.
Really though, if you can get him neutered it will be the most helpful. It helps get rid of that hormonal behavior. It can be a little hard for them right after the surgery, and complications are sometimes possible, but it most often isn't that stressful for them to go through if done correctly.
