Inside the caves are some seriously aggressive monkeys that will attack you if you have food. I wouldn't recommend feeding them or taking any type of food into the caves! Don't attract the scary monkeys!
Some of these monkeys are very aggressive and may attack you when you carry something that might looks like foods to them. Some of the worshippers have problem to bring their offering safely up the stair without being harassed by these monkey.
My advice is, don't feed the monkey!!
in this area of batu caves tamples, there are a lots of monkeys around, but i did not see any of it on the day i was there, but just becareful coz sometimes monkey will attack people for some reason... and when i was there it was just a lost dogs bump on my legs and he try to find his way out... i am not sure if he can find way out or not... to many people blocking his way... so he was just run at the same place most of the time... hehehehe, that funny though.