Moles will not intentionally harm
plants, however, if their search for food brings them into your veggie garden, I doubt they will have the common courtesy to go around the
plants instead of going through them.
I can not think of any chemical ways of ridding moles from a veggie garden, but there is a small device which emits ultra sonic sounds which humans can not hear, which sends the little critters scurrying for the hills, or at least out of range of the sound which is usually about 25 feet away.
You can get them pretty much at any garden center and most hardware stores.