Block Url Link in Message Body Before Message Delivery

Agree with Dan_Snape - Safe Links is probably the  best option although I'm not sure it's going to fit your particular use case; if MS deems the link safe (as in it has good reputation, doesn't have Malware or actually appear dodgy) but you don't want users to go to the URL for other business reasons, then it won't actually block the link. Other solutions approach that if an email contains the specific url the email is either sent to quarantine or otherwise held for review. 

Unless I've completely misunderstood your requirements my recommendation is that if you don't want your users to go to a specific URL is to use a web filtering solution to stop users from being able to go to the link that way rather than try to change the email itself.

It's also possible that a 3rd party mail filter solution might be able to do this, but off the top of my head I'm not sure if any of them do.