No. Dreams are several things. They are your unconcious mind dealing with the day's events- or ideas, events, situations, thoughts, people, words that you haven't dealt with consciously in the past.
When you are awake you think things through logically then abstractly. But with dreams, it's backwards. It's abstract first then logic.
Your dreams do tell you things because, again, it's your unconscious mind bringing to your conscious mind things that you've innocently ignored or purposely choose to not deal with.
You are the only one who can correctly interpret your dream. If you are dreaming that the girl you like shoved you, then the teacher came in and you yelled at her, it could be many things. But only one is right. I can give you some examples but you're going to have to be the one to search yourself to find out what the dream means.
The girl shoving you could be your feelings for her are pushing you beyond your normal limit or where you want to go emotionally. Teacher could represent authority or morals or any other "reasons" that put a stop to these feelings. You yelling at her could be your unconscious yelling at your feelings that they're pushing you too far or too quickly.
Or the dream could represent something totally different, such as a reenactment from a forgotten memory in the past. Perhaps someone you cared about pushed you and they resemble the girl you like. Perhaps the dream is part of a movie or television show you watched before sleeping. Maybe one of the characters in the show did something similar to a person that liked them and unconsciously it bothered you.
But this is all a guess. If none of that resonated immediately with you, then the guesses aren't correct at all.
You'll have to search your own self to find out:
"Why am I feeling this way/thinking this way?
Did something external (such as a movie, a conversation, the neighbor's fight next door, etc) get lodged in my unconscious and filtered in my dream?
Was this an echo of my past that I haven't dealt with?
Is this how I am feeling somewhere now in my life?
Is this something I fear will happen in the future?
What is my unconscious mind trying to tell me?"
Yesterday is history,
Tomorrow is a mystery,
But Today is a gift~
That is why it is called The Present.