Okay, I was able to create something that might help you.
Here's the JSFiddle: JSFiddle
What I basically did was I wrapped the like button in a div with hidden overflow. Only problem is, the comment box appears for a second right after loading the page, but goes away after. (it's still contained inside the div, but it covers up the like buttons for a second)
Another approach could be something like this: Changing iFrame elements
Where you would need to view the source and check Facebook's element id for the comment box. (looks like it's div#u_0_6._56zz._56z
) Once you have the id you can try to .hide()
or .css('display', 'none')
Unfortunately, this id is really obscure and looks to me like it changes on a regular basis. So if it does change, your code obviously won't work.
The JSFiddle does seems to work. And it looks like your only sure option.