Attacking own craetures vs. Vigilance no interaction?

The wording on Vigilance is as follows:
This creature intercepts attacks on its allies, but when it does, it takes extra damage equal to 10% of its Maximum Health.

If a monster attacks an allied monster and another one has Vigilance (all in my group) then Vigilance does not kick in and the attack is not intercepted.

If this is working as intended, then the wording should be changed accordingly.