Yes. Assuming your saddle is where it needs to be, the stem is the ideal part to change in order to reduce the reach. As Broctoon said, a handlebar with a shorter reach will do the same (except it won't affect your reach on the "tops" position). Considering your comment that the saddle is as far forward as it can go, however, you just might be on a bike that's way too big for you (especially if it's a zero setback seatpost). Steve's suggestion to have an expert fit you is a good idea in this case.