You Do Need power plug adapter while traveling from Pakistan to Cuba.

Here is Why You Need An Adapter

The outlet and plug type used in Cuba are A, B, C and L and in Pakistan are C and D. This is how they look like.

Pakistan

In Pakistan, outlets of type C and D are in use.

Type C

Type D

Cuba

In Cuba, outlets of type A, B, C and L are in use.

Type A

Type B

Type C

Type L