Most of the humans in the Vampire Knight world are unaware of the existence of vampires. Due to agreements made between the hunters, vampires and the various human governments after the last set of wars, the existence of vampires is kept a secret. Presumably this is to avoid the possible panic and other issues that could arise from humans realizing that they are living alongside a race that can potentially view them as a food source. It is implied that those in human governmental positions are aware of both vampires and hunters and cooperate in keeping their existence a secret although this is never directly shown.
The fact that both vampires and hunters appear to possess the power to selectively erase and manipulate humans’ memories makes it easier for them to continue the pretence.
Many humans, although unaware of what they are, are naturally drawn to vampires because of their unusual beauty and charm. This can be easily seen in the obsessively fanatical way the Day Class students at Cross Academy often behaved towards the Night Class students.