Who should pursue a Ph.D degree?
So, here's my question: If I say "I'm considering to do PhD" and ask
  your advice, what would you ask me? What kind of
  skills/characteristics do you look for a potential academician?


The first questions I would ask is: are you really interested in the subject? Can you imagine spending the next 5+ years thinking about pretty much nothing else?
Why do you want to do a PhD in the first place?


  However, currently I am working on a conference paper and I feel like
  even that is too much for me. It has been nearly 3 months and still,
  the paper draft is to be improved (not the wording but the content).


Now imagine the same thing but replace 3 month with 3 years.


  Sometimes, I let go of my  work and absorbed in other stuff.


This is also not very helpful for pursuing a PhD.

I think in most fields (that might be different for some fields of science) getting a PhD is only for people who want to do research. Apart from that it is only a waste of time and money. So the question you should ask yourself is not: Am I able to get a PhD? But rather: Do I want to get a PhD?

However, if you decided that you really want to give it a try: talk to someone from your university about it, maybe the supervisor of your thesis. Grades are not always a good indicator of the quality as a researcher.



EDIT:


  My life-goal is being a professor. And I love to do research.


That answers most of the questions.


  But I don't know if I'm capable of doing a Ph.D.


No one here can answer this question. You should try to talk to a professor at your university, the supervisor of your Master's Thesis, or someone who is doing research you are interested in. However, do not let your grades disencourage you, I know many students who had pretty bad grades but are great as PhD students and many excellent students who struggle with their research.