Daisy --
Regardless of the cause, that type of behavior is unacceptable in the workplace. You need to address it head on with the individuals before having any type of group intervention.
Schedule sessions with each team member and conduct some exploratory questioning to determine what might be causing the behavior.
Start with giving some feedback about the person's behavior. Be specific. For example -- "John, I noticed when Sandy was talking about her suggestions about the new process that you were rolling your eyes, but you didn't participate in the discussion. Can you help me understand what that was about?"
If you need some feedback guidelines, take a look at
http://www.teambuildingtips.com/team-building-articles/team-communication/the-dos-and-donts-of-giving-feedback.html
Once you've done your exploring in individual sessions, then you can determine what group activity to conduct. It may be helpful to do a role clarification to help renew focus toward the organization goal.
Give these suggestions a try and let us know how else we can help you.