Police are guides / angels in a dream. Their presence is a reminder that your guides are aware of everything you do and are there waiting to be asked to help.
If a police officer is giving you a ticket it means you are failing in your obligations or life purpose in some way. For instance a ticket for drink driving means you are being told that drinking alcohol is affecting the pursuit of your goals. A parking ticket is telling you that now is the time for action – set goals and pursue them.