Allow blocked content for a specific uri

I actually am talking about an 11.4 "policy". I misspoke before when I mentioned a rewrite profile - a completely different thing. A policy can be used to enable/disable ASM (among many other things) based on some inline criteria. That said, a policy can only act on the request URI and headers, and not payload. So to do what you're asking, to disable ASM processing for specific content, you may necessarily have to use the ASM::disable command inside an iRule that inspects (at least the beginning) payload of each request.