A lot of Christians argue that it does say exactly that. In Genesis 2:15, God tells Adam to care for the planet:
The Lord God took the man and put him in the garden of Eden to work it and keep it.
Of course fundamentalists tend not to see it that way.
> Do not love the world or the things in the world. If anyone loves the world, the love of the Father is not in him.
John 2:15