Personally, I'd push-back on the copy editor's choice of "ice-berg". If you're unable to convince the copy editor, then as other's have mentioned, speak with, or exchange email with, the editor for your submission, if that's a different person than the copy editor. If you don't get satisfaction from the editor, you can raise the issue with the publication's Editor in Chief. Obviously, your final recourse is to withdraw your paper. Only you can determine how much of an issue this is for you and how far down that road you want to go.
In discussions, I usually find that it's important to have evidence to back up your choice.1 It would be good to have a sampling of papers in your area showing which version of "iceberg" vs. "ice-berg" is predominately used. I also find that for this sort of discussion, it's often convincing to use information from Google Book's Ngram Viewer (info).
For "iceberg" vs. "ice-berg", Google Book's Ngram Viewer shows that "iceberg" was used 344 times more often than "ice-berg" in 2008, and has been the dramatically predominant form, at least in Google Book's corpus, for more than 200 years:
You can also look "iceberg" up in various dictionaries. All of the ones I checked didn't even give examples of the hyphenated version.
1. Something just being your preference is also valid, but that's not the case for this issue.