No, I don't believe that, if it is life, and it is made out of atoms and uses energy, then it is not too small to see, or at least detect with a microscope and since it is alive we would be able to detect the energy and chemical processes by which it lives. Life as we define it is governed by physics and chemistry. We are quite able to detect physical and chemical reactions.

Having too broad a definition of life, leads to nonsensical conclusions. Are planets alive? Is your alarm clock? Both have some of the aspects of life. But it makes no sense to call them alive.