As the title said, I just created a Monk character. He get proficiency bonus for Attack Rolls, but NOT on Damage Rolls.
Got this stat for his Attack Actions:

Is this intentional? Because I didn't read anything on PHB that prevent monks for having Proficiency Bonus on their Weapon Damage Rolls like any other class.
Here is my character sheets: https://ddb.ac/characters/30457825/sZD6gv

Quote from Tzexes >>

As the title said, I just created a Monk character. He get proficiency bonus for Attack Rolls, but NOT on Damage Rolls.

Is this intentional? Because I didn't read anything on PHB that prevent monks for having Proficiency Bonus on their Weapon Damage Rolls like any other class.

 Nobody gets to add Proficiency bonus to their damage rolls. 

Damage Rolls

Each weapon, spell, and harmful monster ability specifies the damage it deals. You roll the damage die or dice, add any modifiers, and apply the damage to your target. Magic weapons, special abilities, and other factors can grant a bonus to damage.

With a penalty, it is possible to deal 0 damage, but never negative damage.

When attacking with a weapon, you add your ability modifier--the same modifier used for the attack roll--to the damage. A spell tells you which dice to roll for damage and whether to add any modifiers.

If a spell or other effect deals damage to more than one target at the same time, roll the damage once for all of them. For example, when a wizard casts fireball or a cleric casts flame strike, the spell's damage is rolled once for all creatures caught in the blast.

Then why is it added to the attack rolls of every other character ever. I have this same problem and if I make a fighter the weapon states that proficiency with the weapon  adds the bonus to attack and damage rolls

Proficiency bonus is only added to attack rolls, not damage rolls. If you have a weapon that states it adds PB to damage rolls it must be homebrewed and there is no way to program that into the homebrewer.