You might also ask in the Long Distance forum and/or the Touring forum, since those are the folks that give the most thought to handlebar bags.

And BTW it is spelled "randonneur," not "rondoneur," in case you're having trouble finding information.

As others have mentioned, some of the smaller handlebar bags such as Ortlieb that use the Klick-fix attachment will fit. Most of the Klick-fix bags should also stay out of the way of your hands on the tops of the bars. Actually, the Ortlieb ones are probably worth looking into because their shape would keep them more out of the way or your cables than a more square one.

You can also look at this handlebar bag: (in interests of full disclosure, Dill Pickle Gear is my company and as such I have a commercial interest)Handlebar Bag
It is lightweight and needs no additional hardware, and is supported by cords that go around the brake levers, under the rubber hoods. On bikes with the old-style Shimano cables that come out of the sides, the easiest way to attach it is to attach the cord with a "Velcro One-wrap" velcro strap (they are cheap and you can find them everywhere). The bottom profile of the bag curves away from the front and the sides taper toward the back (to keep the bar tops free for your hands) so that on almost any bike there's a place for the cables to coexist with the bag. I designed it specifically with randonneuring in mind.

Lastly, depending on the geometry of your bike, you might think carefully about how much weight to put up front. There are a lot of variables, but many standard road bikes don't react well to more than a few pounds up front, depending on where the weight is positioned. If you can ask around for other experiences with putting handlebar bags on the same model of bike that might not be a bad idea. You probably don't have room around your cables for the largest handlebar bags anyway, but something like this one Arkel Waterproof Handlebar Bag - Large would probably be a bad choice because it weighs three pounds even before you fill it, and puts the weight fairly high and out in front of the bars, so it would be much more likely to adversely affect the handling than something like this: View the ULTIMATE 6 M CLASSIC at http://www.ortliebusa.com which is smaller, lighter, and doesn't stick so far out to the front.