I have medium amateur skills in Python and I'm beginner in asm and haven't any knowledge of C-language.
I know that python C-extensions must follow specific interface to work fine.
Is this possible to write python extension in pure Assembly with the right interface and full functionality? The second question is would it be efficient enough if case of doing it right?
While googling I haven't found any examples of code or some articles or solutions about this question.
And this ISN'T the question about running asm-code from within Python so it's not duplicate of topics on SO.
You could write your asm as inline asm inside your c extention, as for efficiency... 

Teapot.

Efficiency isn't measured by the choice of language, its measured by how well its implemented and how well its designed.
How to write python extensions in pure asm and would it be efficient?