I am not able to install any Python libraries. I am using pip 9.0.1 and python 2.7. I am getting the following error:
EN-NishantS:~
Your HTTP request to PyPI fails with an HTTP 403 (Forbidden) error:
HTTPError: 403 Client Error: TLSv1.2+ is required for url:
https://pypi.python.org/pypi/pip/json
Apparently pip is trying to access PyPI via HTTPS (which is encrypted and fine), but with an old (insecure) SSL version. Your system seems to be out of date. It might help if you update your packages.
On Debian-based systems I'd try:
apt-get update && apt-get upgrade python-pip
On Red Hat Linux-based systems:
yum update python-pip # (or python2-pip, at least on Red Hat Linux 7)
On Mac:
sudo easy_install -U pip
You can also try to update openssl separately.