Monkeys are funny, as well as dangerous.
I have already asked a question about how one should go about camping where there are monkeys around: Camping and Monkeys.
The best advice would be to avoid them if you are unsure about your own safety.
A number of Rock Climbing places in India are habitats for these monkeys, living in the natural caves, playing all day on the edges and cliffs. As a climber, I have always seen that when I am at the base of one such climb, as I approach they panic.
Have other people in the rest of the world had a similar issue? What would you do if you have climbed up a good way and then you find a gang of monkeys up over the wall? Is it wiser to call it a day and retreat?