1st
As you said they are spoiling the working atmostphere. Interact with them personally and tell them not to spoil the working atmosphere. but before doing that have some proof wid you so dat they cannot do anything wrong wid you and dont think about personal life. personla life is after office timings not in office timings.

2nd
issue a common notice for all and bring it to notice of higher management without telling the names of the persons those doing the same, so that nobody claims that you are doing such things due to personal traits.