No, they are not harmful. They are very curious, but they will not harm you. It can become a problem when people want to spoil them (even with good intentions) by feeding them. Then they start seeing humans as a source of easy food and it can cause problems, especially if they think you have something and you don't want to give to them. But as long as we respect them and enjoy them as wild animals and don't disturb them, they won't harm you.