It certainly is an order, meaning: "Don't go out until you've finished this."
It has the form of present continuous: "are [not] going."
But it's actually present continuous used as future, which is very common in colloquial English.
In this case, it sounds like a person in authority is speaking, perhaps a teacher or parent. I think you'd use this structure if you were talking to a child, not to a friend or co-worker.
Student or Learner