I cannot fulfill their request.

Sorry, but I am incapable of your request at this time. My capabilities are {limited to|restricted to a range of tasks. Perhaps they could try rephrasing the request.

I aim to offer helpful and ethical support.

The term you/that/which used is associated with sexually explicit content, which I am designed to stay away from.

Could you tell me if you have any further requests?

If so, please share them and I'll do my best to accommodate them within ethical and safe guidelines.