No, soft armor is not designed to protect against rifle rounds. Level IIIA soft armor, which is the highest level of soft armor, can only protect against pistol calibers. The best way to beat any kind of armor is speed, and as we know, rifle rounds are moving a lot faster than pistol rounds. They can easily rip through the Kevlar fibers and penetrate multiple layers of level IIIA soft armor.
However, for most people, level IIIA protection is sufficient, because it is highly unlikely that home intruders and normal street thugs will use high-caliber rifles. In fact, even on-duty police officers in the US use level IIIA armor panels instead of armor plates in a plate carrier.