I have played a warlock for a long time, and as far as i know we do not have a interrupt, but they have re-designed the class a few times.
A few times while questing or exploring in MoP i would come across one of them elite panda mobs you can take out. I could take them out just fine, except they have a heal that heals them to full, and as far as i know, i have no way to interrupt it.
I swear every class has a interrupt now, please tell me warlocks aren't the only one without one? lol