A polite way to communicate the message "don't raise your voice at me" is to use assertive and respectful language. Here's a possible phrase you could use:
"I would appreciate it if you could please lower your voice. Let's discuss this calmly and respectfully."
In this response, you're expressing your request in a calm and composed manner while emphasizing the importance of maintaining a respectful tone during the conversation. Using "I would appreciate it if..." helps to frame the request in a polite and non-confrontational manner.
Remember, communication is key, and addressing such situations with politeness and respect can often lead to better outcomes and a more constructive dialogue.