I think it would be more natural: My dream is to be a teacher. When we say "my dream is" the "I want to" is understood.

"My dream is to teach." "My dream is to be a teacher." Either of those is better.

Agree with Brooke and Susanne. Just leave out the "I want" and you're fine. Remember, brevity in English is the best style if you don't lose the meaning of what you want to say. Avoid unnecessary words and verbiage. A good rule of thumb.

My dream is to be(come) a teacher. I dream of be(com)ing a teacher. I hope to become a teacher one/some day.