Use Security preferences in Safari to block or allow pop-up windows in Safari, and turn security warnings on or off. To view these preferences, choose Safari > Preferences, then click Security.
Warn when visiting a fraudulent website
Safari warns you if the site you’re visiting is a suspected phishing website. Phishing is a fraudulent attempt to steal your personal information, such as user names, passwords, and other account information. A fraudulent website masquerades as a legitimate one, such as a bank, financial institution, or email service provider. Before visiting a website, Safari may send information calculated from the website address to Safe Browsing providers to check if the website is fraudulent.
Block pop-up windows
Block ads displayed in pop-up windows that appear when you open or close a webpage. However, some websites use pop-up windows for essential content.