Restrict OSX applications from using the network
You might be interested in TCPblock app.




  TCPBlock is a lightweight and fast application firewall for Mac OS X
  10.6 or later developed by delantis.com. The Mac OS X firewall protects you from connections that come from outside of your computer.
  But what about the software from your computer that opens new
  connections to the internet? With TCPBlock you can prevent selected
  applications on your computer from opening connections to the network.
  TCPBlock is implemented as a loadable kernel module which contains all
  the blocking logic. You can configure it in the System Preferences
  TCPBlock preference pane or with the tcpblock command line utility.
  All the configuration changes are made persistent in a configuration
  file on the hard disk. At system boot time the TCPBlock kernel
  extension reads its configuration from disk and is ready to go.