The rules state on page 13 under the heading Enemy Attacks:
When an enemy activates on the same tile as a valid target, it attacks. A little bit below that, you can find
Players are always valid targets, ....
Page 14 also states clearly under the heading Enemy Movement:
If an active enemy has no valid target for an attack, it moves one tile. (my emphasis)
Thus, if you are on the same tile as a clone or guard when it activates, a tastier target on a different tile will not save you from the attack.