He's not aggressive he is just trying to get your attention directed back towards him and it sounds like it is working
Honestly the best thing to do is ignore him when he does this not even making any eye contact with him. After play time is over and he starts just get up and walk away from him totally ignoring him and just go about your business. It will take him a little while but he will get the picture that play time is over because you say so.
Of course get him neutered! If you are not showing him or have no intentions of completeing all the health tests in order to breed him then there is no reason why he should not be neutered. It is much much better for his health and in his best intrest to have him neutered
Please use the search function on both neutering and the above behavior and you will find lots of threads with information and tips. Good luck and enjoy your puppy