My dog gets angry when I shout?

I have a small Maltese female puppy who is VERY fond of peeing and pooping on carpets ONLY. She sometimes pees on her pads.. and if not, its on the carpets. So we do not allow her to go outside to the living room. However, there is no kind of baby gates put up yet.. So whenever she does it, and I shout or like raise my voice to with a firm NO, she just roars and growls at me.. It actually scares me, even though she's so tiny. I've had bad experiences with aggressive animals, so I dont know what to do!