Is "lowering the gaze" in the noble verse: "Tell the believing men to lower their gaze" exclusive to believers, or does it include Muslims and people in general?

The reason for specifically addressing believers in the verse: "Tell the believing men to reduce [some] of their gaze and guard their private parts" is that they are the true beneficiaries of this command and are capable of adhering to it. This does not mean that non-believers are not addressed by the verse. The correct view is that disbelievers are indeed addressed by the branches of Islamic law, but their deeds are not valid unless they first embrace faith. The consequence of their abandonment of these commands will manifest in the intensification of their torment in the Hereafter.