I would say: The manage doesn't want to get in conflict with the staff, so he decided to designate a representative to deal with them.

I would say, “ The manager doesn’t want conflict when speaking with the staff so he has chosen a representative to speak with them instead.”

Hi Ramin, You may say: "The manager didn't want any conflict with the staff, so he assigned a person who will be responsible on his behalf in dealing with any staff inquiries and other matters." Have a great day!

To avoid conflict with the staff, the manager assigned someone who will be handling questions and queries, you can relay anything you would want the management to know.

Hmm... It's difficult depending on the context, but if I understand you correctly, I would say something like, "The manager doesn't want to engage in conflict with the staff, so he has appointed a representative to deal with the situation."