yes, it will affect your strength levels. You can probably do a little cardio without hurting anything, but as Dave Tate says, you cannot run a 4 minute mile and bench 400 at the same time.
You would probably be better off doing some sled dragging 3 times per week if you are interested in attaining maximal strength and fitness.
If for some reason you have to be able to run some distance, for military, or football, or something, then just realize that you can do both cardio and strength training, but that one does work against the other.
B