I found some solutions on The Helper Forums..
Solution 1
You can classify the unit as peon or worker if you do not want it to auto-attack in all instances possible.
Solution 2
The acquisition range is the maximum range for ranged attacks.
If you set an archer which has 1000 range, and gave it 100 acquisition range, the archer's range will be reduced to 100.
Solution 3
Replacing the unit with a "no target" unit.
RESULTS:
Solution 1: Works Perfectly
Solution 2: Not Tested
Solution 3: Doesn't Work