The rebel forces are not Al Qaeda, as in they are separate entities with separate leaderships and intentions.
I have heard, however, that Al Qaeda has been supportive of the rebel forces. They are trying to gain PR with the Syrian public. In a way, this is actually a reason to support the rebels. If the rebels win, and Al Qaeda supported them, then the new government will be an ally with Al Qaeda. If the rebels win, and the U.N. supported them, then the new government will align with the U.N. This reminds me of the time when Al Qaeda provided flood aid to Pakistan.