Yes, I believe it would. There are typically instructions on the product label that inform you on when it is safe to plant following an application of pre-emergent herbicide. If you send me the name of the product I can give you some more detailed information on the effects it could potentially have on lavender. I would need the brand and product name to provide more information though.

Dual Magnum is approved for use with the following crops: corn; cotton; grasses grown for seed; horseradish; legume vegetables; peanuts; potatoes; pumpkin; rhubarb; safflowers;
sorghum (forage, grain and sweet); soybean; sugar beets; sugarcane;
sunflowers; and tomatoes

Using it where you're growing lavender, would be an off-label application, which is illegal. Do not use this product where you're growing lavender.

Prowl H20 is approved for use with the following crops: 

alfalfa
artichoke
asparagus
Brassica head and stem vegetables
carrot
citrus fruit trees, bearing and nonbearing
corn (field, field seed, fresh sweet, popcorn, popcorn seed)
cotton
date palm trees, nonbearing
edible beans
fallow
fig trees, nonbearing
forage grasses (cool-season)
forage grasses (warm-season)
fruiting vegetables
garlic
grain sorghum
grape, bearing and nonbearing vineyards
hops
leek
lentil and peas
melons
mint
nut trees, bearing and nonbearing
olive trees, bearing and nonbearing
onions and shallots (dry bulb, green)
peanut
perennial grasses grown for seed
pome fruit trees, bearing and nonbearing
pomegranate
potato
rice
safflower
soybean
stone fruit trees, bearing and nonbearing
strawberry
sugarcane
sunflower
tobacco
triticale
wheat

As you can see, lavender is not listed, so this herbicide would not be appropriate to use either.

Treflan HFP label states: A herbicide for the preemergence control of annual grasses and broadleaf weeds in Alfalfa, Almond, Apricot, Asparagus, Barley, Beans – All Dry and Fresh Beans/Peas, Borage, Broccoli, Brussels Sprouts, Cabbage, Calendula, Carrot, Castor
Oil Plant, Cauliflower, Celery, Chicory, Chinese tallowtree, Collard Greens, Corn, Cotton, Cottonwood Trees Grown for Pulp, Cucurbits, Cuphea, Dry Peas, Durum, Echium, Eggplant, English Peas, Euphorbia, Evening primrose, Flax, Flaxseed, Grain Sorghum, Grapes, Grapefruit, Guar, Hare’s ear mustard, Hops, Jojoba, Kale, Kenaf, Lemon, Lentil,
Lesquerella, Lima Bean, Lunaria, Meadowfoam, Milkweed, Mungbean, Mustard Greens, Mustard Seed, Nectarine, Niger seed, Oil radish, Okra, Onions, Orange, Ornamentals (Trees, Woody Shrubs, Groundcover, Roses, and Established Flowers), Peach, Peanuts, Pecan, Pepper, Peppermint, Plum, Poppy Seed, Potatoes, Prune, Radish, Rapeseed, Rose hip,
Safflower, Sesame, Snap Bean, Spearmint, Southern Peas, Soybeans, Stokes aster, Sugar Beets, Sugarcane, Sunflowers, Sweet rocket, Tallowwood, Tangelo, Tangerine, Tea oil plant, Tomatoes, Turnip Greens, Under Paved Surfaces, Vegetable Gardens, Vernonia, Walnut, and Wheat.

Since Ornamentals are listed, you could use this product where you plan to grow lavender, but realize that it says "established flowers" (also lavender is not one of the flowers listed, so there has likely been no testing with that crop). You should not use this product around new plantings of lavender that aren't well established.

If you do decide to use this or any other product, make sure you read the entire label prior to application. Also, consider some alternative weed control measures to herbicides, such as using a mulch material.