Nope. That's all on the users end and beyond your control.
They can allow it once and have it remember from there on out or they can add you to their trusted sites.
If you could bypass it on your end, there wouldn't be any reason to have that feature.
There have been many complaints about the pdf security warnings, just search the Adobe forums here.
As I suggested in my original post, perhaps Adobe is willing to issue security clearances similar to the ones Symantec does for Norton Internet security.
Since I get a security warning for adobe.com, I don't think Adobe are giving out exemptions.