This is triggered by the IPS component of SEP. Full details are here:
https://www.symantec.com/security_response/attacksignatures/detail.jsp?asid=28821
Basically it looks like the site may have been compromised and re-directing users to other malicious sites.
SEP is doing its job by blocking the potential attack.
Here's the URL it triggers on:
I would verify the site has not been compromised.
Take a look at that main.min.js file, it has hidden iFrames in it..is this intended?