If you're a stickler for language, then yes. The word "can(not)" refers to the ability, while the words "may (not)" or "must (not)" refer to a policy constraint rather than ability.
But in common vernacular, the word "can" is used in both cases, so it's ambiguous.
"Mom, can I play on the Xbox now?" "No, you haven't finished your homework." Obviously Junior has the ability to play, but his mom won't allow him to do so.
