Using a meta NOINDEX tag at a URL level will prevent Search Engines from indexing that URL but in order to detect the tag, which is located within the HTML, the page needs to be crawled. If you are linking to a large number of pages from within your website that has a NOINDEX tag, they will all be crawled on a regular basis. A NOINDEX tag, therefore, does not impact Search Engine crawling but instead the indexation of pages.