You can do this. They will not auto attack anything but mines if its disabled. That is because when a scout reveals a mine, it automatically attacks it. So your problem lies elsewhere. I can only assume you have the scouts in your fleet and you rightclick to attack structures with your fleet and the scouts move to attack also, that's not autoattacking, they actually receive order to do so. Also, even if you do not tell them to attack but they are part of the fleet, they will move with ships that are moving to attack because they want to stay in formation.
And yes people do make fleets of scouts. They are very good at killing neutral siege frigates and lrms, paving way for colonization.
