I want to clarify, this answer is possibly incorrect due to the fact that I can not comment asking for clarification on versions. I do not have 50 reputation at present time. If it does not work, I apologize.
Well there are two things that can be happening. When I tested this, I was able to install Tensorflow using the same console command that you did. Although I am running Python 3.8.3. Try updating python, and updating Pip.
(To update pip, simply type "python -m pip install --upgrade pip
" and to update python, reinstall it.)
If that doesn't work, use Karthik's response of directly referencing the link to the repository of Tensorflow. Command being - "pip install --upgrade https://storage.googleapis.com/tensorflow/mac/cpu/tensorflow-1.0.0-py3-none-any.whl
". Hopefully that helps.