They did die. Death entered the world when sin did, because sins lead to death. And He *told* them not to eat the fruits because they will surely die when they do. It's not God's fault that Eve and Adam used their free will to disobey God, just like if you touched the stove when your parents told you not to because they know if you do, you'll get burned, it's your fault, not your parents'.
...Oh, I forgot, you want a God who shelter us from all possibilities of bad things happening from the very beginning of creation even if that means we lose our free will. My bad.