I think that requirement would conflict with some open source licenses -- they typically grant the right to redistribute and modify the source code in any way.

That would include stripping out everything but the icons and selling them.

So if the license requires all accompanying code/assets to be under similar licenses, that could prevent use of your icons. I think that's the case under the GPL? Not really sure anymore.

e: After doing a bit more reading, I believe I was wrong. As long as the icons aren't somehow compiled into the binary, there are no license problems.

It sounds like you want

http://www.tldrlegal.com/license/CC-NC

No, this differs from CC-NC in that you can use them in a commercial work, you just can't sell them on their own. Using CC-NC would prevent users from bundling these into a commercial product whatsoever.

In that case...

Public Domain and CCZero would be a very efficient way to quiet people's fears about what they can't do with this icon set, without alarming them that they need Legal Advice to build their app. You've tried to trim down the restrictions to almost nothing, but we have an established protocol to encompass all uses. Why not go all the way?