You might want to look into the William & Mary/St Andrews joint program. International Relations is one of the six majors you can do in that program:
Then with interests in IR and Arabic, I assume you are already looking at George Washington and American (if not, you definitely should be!)
A little bit more outside the box suggestion would be Bucknell. People usually think of it for other purposes, but it actually has a robust and reasonably popular Arabic Studies major, which includes studying Arabic:
Or you can do it as a minor if you like.
Another with a robust program along those lines is SUNY Binghamton:
Again it is available as a minor as well.