It gets complicated doing this... I personally hated the way Google handled contacts. So I use only icloud now. But if you want to do this. Go to your contacts on icloud. Website side, and highlight all your contacts. Export them by clicking on the cog at the bottom. It will export them as a Vcard for however many contacts.
Then log into your gmail. Erase all the contacts, if you don't you will probably end up with duplicates.
In contacts import your Vcard and then turn off the sync options for your phone for icloud.
I did have to quit using google.. i lost information during syncs and tons of addresses. It was driving me nuts.