Blocking Goolge crawler using "robots.txt" file
To stop google news crawler from indexing your site add following lines in "robots.txt" file.
User-agent: Googlebot-news
Disallow: /
This will block your entire web site.
To block specific article/ page use following:
User-agent: Googlebot-news
Disallow: /<path>/<page-name>.<ext>
Note: Replace <path> with path of article and <page-name> with name of page and <ext> with extension of that page for example .html . php .htm .asp ect
Blocking Goolge crawler using "<meta-tags>"
Add following meta tag in <head></head> section of page.
<META NAME="Googlebot-news" CONTENT="noindex" />
This will tell Google crawler that you don't want to include this article in google news.