Block Google from indexing WordPress Images?
If you want to block Google search bot from crawling and indexing images in your uploads directory, and core internal files. Follow the technique below:
Create robots.txt file in your WordPress’ root directory and add the following content.
User-Agent: * Disallow: /wp-content/uploads/ Disallow: /wp-content/plugins/ Disallow: /wp-admin/ Disallow: /readme.html
This instruction file is for search bots and it shows your preference on what to be indexed and what to be left alone.
Note that, there are a dozen of web crawlers like Google, Bing and Yahoo. There are others besides these heavyweights as well and it totally depends upon them, whether they honor your request or not.