You Do Need power plug adapter while traveling from Iran to Lebanon.

Here is Why You Need An Adapter

The outlet and plug type used in Lebanon are C, D and G and in Iran are C and F. This is how they look like.

Iran

In Iran, outlets of type C and F are in use.

Type C

Type F

Lebanon

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

Type C

Type D

Type G