A restraining order is the result of a civil action. What you are looking for may be called an order for protection or something similar in your state. It may be something you obtain from a lower court like a justice of the peace; check with them also. Some prosecutor is bound to file cases like this. ( In my state, the DA only handles the most serious of crimes; things you would go to prison for. )
There is probably something similar to our 'tresspass warning' also. It is given by the police to the tresspasser so that if he comes back, he will be arrested for tresspassing on the spot. Again, this is in Texas. You may have something similar, but I bet you have something.
If you can't go to the police station in person, call them back and ask for the investigator on duty. Tell him or her that you are the victim of a terroristic threat and then tresspassing from the individual representing that he was acting on the part of the DA's office and that you want to press charges for all offenses. Ask them to file a complaint on your behalf. If the police will not do their job (don't be surprised if they won't), call your city council member or alderman and complain. Tell everyone you talk to that you are in fear for your safety. I don't have time to do it now, but I'll look on LawHelp.org to see if they have some info for you too. Don't take no for an answer.