At 11 mos. I just keep saying no in a firm calm voice and made eye contact, by holding hands if need be. You're right. . .she obviously understands you. However, she has no way to say, "Gosh mom, I really wish you'd reconsider!"
At that age, we also worked on teaching "gentle touches" although I can't remember if we did that for the other kids or not. With the twins it was an absolute necessity!