Google ignoring robots.txt

I have set a robots.txt so that all robots ignore my wp-content folder as well as wp-admin and wp-includes and google still indexes them. I want to make sure I am doing it right. This is my robots.txt file

User-agent: *
Disallow: /wp-login.php/
Disallow: /wp-admin/
Disallow: /wp-includes/
Disallow: /wp-content/
# BEGIN XML-SITEMAP-PLUGIN
Sitemap: https://mywebsite.com/sitemap.xml.gz
# END XML-SITEMAP-PLUGIN

It should be following my robots.txt shouldnt it? I looked around and I see that this is how its supposed to be written. Please help, because its also indexing my plugins and other files I dont want people to have access to.