Can a master's student change their mind and look for a different project?
Of course you can tell him anything. However, from your description, be prepared for consequences. If he is really committed to this project it is just possible that your speaking out will destroy any future relationship with him. If it is possible to change advisors think about doing that if it starts to go bad. You can't just work without an advisor and you need a good relationship with whoever you have. 

On the other hand, assuming he has more perspective on these things than you do, it may just be that fighting through your reluctance is the right course for now. Three months isn't a terribly long time if the project is significant. However, I don't understand why he is committed if he also thinks it isn't a good candidate for publication. 

But if neither option is available to you, it seems like you are just stuck. It isn't a good place to be. And not having another project to substitute it is hard to find a way out. 

Switch advisors if necessary, or push through it. It might even be that some small success in the current project will let you change your opinion about it. 

If you anticipate switching advisors, talk to another professor first who is willing to take you on before you make a break with your current advisor. Don't leave yourself unsponsored.