Selective contacts on iphone
iOS will show all contacts under "My contacts" on Google / Gmail.
If you move contacts out of that group, they will not show on your iPhone.  

To do that, go to http://gmail.com and login with your credentials.
Click on Mailon the top left and select Contacts.



There you can see which contacts are on which groups and move the contacts you'd like to hide from iOS (and OS X, by the way) out of "My contacts".

This has even helped me when deleting contacts by mistake, as they don't dissapear from your Google account, they just get moved to "Other contacts".

You can group them if you like but those groups will not be available or selectable for display / hide on your iPhone on the standard configuration. When you have multiple contacts lists from different accounts, a Groups option appears on the top left menu on the Contacts app, and Google Apps may show Address Book and Global Address Book as options, but the latter will take you to an empty list designed to search from the organization list of addresses. Or –as of right now on my iPhone after showing me those options– it may show you only one option per account (All (name-of-the-account)), to toggle on or off.