If you have noticed an error like this on your browser while visiting your website, it means your website file contains malicious or infected files which Google bots have detected. There is also a possibility that your website is compromised or hacked.
You can clean up the malicious files and review your website using Google Webmaster Tools.
Step 1: Go to Google Webmaster Tools Page - https://www.google.com/webmasters
If you have a Google account, you may login to Webmaster Tools using the same credentials. Otherwise you need to create a new account and login.
Enter your domain name in the text box and click on the button ”Add a site”.
Step 2: Google will provide you with a set of instructions to verify the ownership of your domain. Follow the instructions as mentioned on this page and complete the verification process.
Step 3: Once the domain is verified, you can view your domain name listed in your Google Webmaster Tools home page.
Click on your domain name and Click on Security issues.
You can check the “Health” section of your site and review the Malware page to get a list of pages that were flagged.
Step 4: You need to clean up the damage that you see as flagged in Google Webmaster. This is, by far, the most difficult part of the process, but the most crucial to disable that nagging Google Malware warning.
Step 5: Once this has been done and you are confident that your website doesn’t contain any infected files or malicious content, you may go ahead a click on the Request a Review button on Google Webmaster Tools. Fill out the form and click on Request a Review
Step 6: Once the review is complete and Google finds no malware, the warning message that appears when you visit your website will disappear. This may take 24 to 48 hours to reflect.