！
Please don't treat me so coldly!
Literal
Cold-harshly [adverbial-に] don't-do-[negative-request-ないでください][assertive-よ]!
A plea against being treated harshly. 邪険 ('harsh, cold, unkind') is a formal na-adjective for cold-hearted or unkind treatment of someone who deserves better. ~にする ('treat as X') with this adjective means 'treat coldly.' ~ないでください is the polite negative request 'please don't X.' The final よ adds urgency or emotional appeal.