The assembler generated codes IS the machine code.
However, deeper inside the typical processor is a further layer of digital hardware, which translates this code into a further sequence of micro-codes, and it is the microcode which actually trigger all the signals required to actually do the job which that assembler code requires.
For example : an assembly code might be a simple MOV A, B
But the actual signals which cause the data from the addressed 'B' latch to appear on the internal bus, and then get clocked into the addressed 'A' latch are all generated using microcode.
nevermind.