Lies as self defence vs. Physical self defence

Why is a lie for the purposes of self defence necessarily unwholesome? Why is using a lie as defence for another from attack considered parajeeka for a monk when a monk can use physical self defence and it's not parajeeka? Why can't a monk misrepresent reality(lie) for self defense instead of resorting to physical violence? As long as you know what the truth is why give it to someone who would exploit it? I was thinking that our intentions aren't unwholesome because we lie but a lie is unwholesome because of our unwholesome intentions. -Metta