Do you wish to stop the search engine to stop crawl the pages. Even no need to index the website pages so that they not visible into the website. Its requirement some time due to lots of traffic on website or even you have own goodwill of website. So all robot of Google, Bing , DuckDuckGo and Yandex will stop.
Just simple you have to add HTML meta tag into the website pages.
If you wish to stop all search engine crawler :
<meta name="robots" content ="noindex" />
Only for google bot :
<meta name="googlebot" content ="noindex" />