Seeing a monkey in a dream could have different meanings as per Islam depending upon the context and situation.
1- According to Ibn Sirin رحمة الله عليه the greatest dream interpreter of Islam, a monkey in a dream represents a cunning and a cursed enemy.
2- Sitting beside an obedient monkey means he shall takeover his enemy and the enemy shall become his obedient.
3- Fighting with a monkey in a dream such that he fears it means that he would become ill, yet would recover.
4- Killing a monkey in a dream means to make the enemy strong and influential.
5- Eating the meat of a monkey in a dream means sorrow and sadness and sickness.
6- Receiving a monkey as a gift in a dream means that someone would show enmity towards the dreamer.
7- According to Jabar Maghrabi رحمة الله عليه seeing a monkey sitting on a horse means that a jew would cause some problems with his wife.
8- Seeing a female monkey in a dream means a witch who does black magic.
9- If a monkey has entered his house in a dream means his wife would do black magic.
10- Talking to a monkey in a dream means that his wife would cause loss to him.
11- A monkey bite in a dream means that the dreamer would become sick or his family would abuse him.
12- Receiving a gift from a monkey in a dream means that the dreamer would waste his wealth.