Screen touch issue with IsPointerOverGameObject

Hi!

I'm making a kind of Flappy Bird game to learn a little bit. For now the game works fine, in Unity works as expected, but in mobile there is something that I can't solve.

I have some UI buttons for different actions and the problem is that when you touch them, the game considers that screen touch as a simply action to make the bird fly. Then the bird flies until the top of the screen and dies.

This is my script and I don't know what I'm doing wrong.

 void Update() {
         if (isDead == false) {
             if (Input.GetMouseButtonDown(0) && !EventSystem.current.IsPointerOverGameObject(-1)) {
                 rb2d.velocity = Vector2.zero;
                 rb2d.AddForce(Vector2.up * upForce);
                 anim.SetTrigger("Fly");
             }
         }
     }

Some help, please?

Thanks!