Interesting ... I would agree with Darren, however, unless you have greatly oversimplified what you consider noise, there are some regions that have smaller clusters yet you haven't circled them. Would be fair to say, that you didn't circle all the noise? What about that big lump in the South East corner... is that noise too?
So follow Darren's suggestion, perhaps with a focal majority with a moderate sized neighbourhood first to get rid of speckle. Then do the RegionGroup incrementally until you get most of what you call noise identified