A well trained Doberman with a strong alpha leader will not act this way for no reason and if there is a false alarm, the dog should trust you enough to obey your command to calm down.
  If you are dealing with an aggressive Doberman, young or old, there are a few things that you can do to gain control over your dog and reduce the risk for a potentially dangerous situation.
Identify the Reason Chances are, you are not dealing with an aggressive Doberman for no reason.
  If you look hard enough, you should be able to find the trigger to the behavior.
  Many people yell at their dog, only to discover later that their water bowl is empty, they are injured or someone was hiding in their bushes.
  Just because you don't think that their actions are justified, does not mean that they aren't.
You need to determine the cause behind your aggressive Doberman Pinscher's behavior and intervene.
  If you remove the trigger, you generally stop the behavior.
Basic Commands If your dog does not know basic commands, you are going to have a difficult time controlling an aggressive Doberman.
  Words such as "No!" and "Stop!" should be taught as early as possible.
  Always be consistent with your training and use the same word so that your dog doesn't get confused.
  If you have always used the word "No!" with your dog and then your Doberman is growling at someone, you cannot all of a sudden use the word "Stop!"  and expect him to understand you.
Be sure to never get mad at your dog for his protective behavior because he is essentially doing his job.
  The goal is to control the action so that your dog will stop on your command, not make him feel as though he shouldn't warn you about danger.
Socialization There is a good chance that you are dealing with an aggressive Doberman because he has been poorly socialized with humans and other dogs.
  You can have a friendly, socialized Doberman and he can still fulfill his role as a guard dog.
  Your dog does not have to be mean to protect you.
  Not socializing your dog results in an aggressive Doberman attacking out of fear.
A Doberman that has been brought up around other people and dogs in various environments becomes confident and fearless.
  A socialized dog will display aggressive Doberman traits when the situation requires it, otherwise, he will be friendly, yet remain alert.
Exercise Physical exercise and mental stimulation are vital to controlling aggressive behavior.
  These are active dogs that will become destructive and aggressive when they get bored.
  If you don't have time to take your Doberman for a long walk or jog everyday, this is not the breed for you.
  Keep in mind, a tired Doberman is a calmer dog.
Additionally, since this is such an intelligent  breed, they enjoy and need frequent training sessions to learn new tricks and commands.
  Teaching them just the basics is not enough, they are far too smart for this level of canine education.
You may want to consider enrolling your dog in obedience or agility classes.
  Even if your dog has already been through training of this nature, sometimes just reinforcing what has already been learned can put a stop to aggressive Doberman behavior.
  This is also a great way to allow your dog to socialize as well.
Never Physically Punish Your Doberman An aggressive Doberman is often the result of poor handling and abuse.
  Inflicting any kind of physical pain on this breed will not discontinue their behavior.
  By making your dog fear you, he will lose his trust in you which will result in him not obeying your commands.
Always keep in mind that aggressive Doberman behavior is based on how the dog has been treated or trained.
  If you are bringing a new puppy home, aim to train your dog properly from the beginning so that you won't have to correct aggressive behavior later.