Simply replace the unfilled areas such as "" and "[date]" with your information.
To all [name of department] Staff Members:
I have noticed entirely too much socializing in the office lately. I understand and appreciate that many of you are friends outside of the workplace, and I commend you for developing a friendly, positive working environment.
However, we still need to put our work first. While some talking and laughing is certainly acceptable, let's please try to keep the socializing to a minimum. Please avoid standing and lounging about the office, and if you have something to discuss that requires a ten-minute break from your work, please save that for your personal break.
Thank you in advance for your help with this.