However, depending on the context, there are many other ways to express "Je n'ai pas envie" in English:
* I don't want to. (This is the most direct translation, but it can be a bit blunt.)
* I'm not in the mood for it. (This implies a general lack of enthusiasm.)
* I don't feel like doing that. (This is a softer way of saying you're not interested.)
* I'd rather not. (This is a polite way to decline.)
* I'm not up for it. (This implies that you're not feeling well or energetic enough.)
* I'm not interested. (This is a straightforward way to say you're not interested.)
To give you the best translation, please provide me with the context of the situation where you would say "Je n'ai pas envie."