Have a different URI and handle them at Apache/Dispatcher to PT (to maintain the same URL) or redirect to /api/*. This would be the easy one for maintenance.
To use PT and retain the original URI/URL:
RewriteRule ^your/custom/uri/$ /api/your/path.json [PT]
The above would internally redirect the request and the user would not see the redirection on the broswr.
You can always redirect the user. Let me know if you want the example.