Is it mandatory to have published papers while applying for PhD? I've heard from people saying that while applying for PhD, you need to have past experience in researching something and should have international publications. I was like more concentrated towards practical experience and have't had any publications. If I am aspiring to do PhD and want to apply, it would be impossible if such a criteria exists!
Is it mandatory to have published papers while applying for PhD?


No.

However, if you have any research experience (working in a lab, research you've done for classes, undergraduate thesis, capstone project, etc.), you should highlight that on your application, both in your personal statement and on your resume / CV.  More importantly, your letters of recommendation should discuss your potential for research. Your recommendation writers should know this, but it would be worthwhile to highlight this in any material you provide to them when you ask them for recommendations, and when you discuss it with them. Trust me, the more information you can give your letter writers, the better their letters will be. I explicitly ask students what their goals are when I'm writing letters of recommendation so I can tailor them appropriately, and you should make sure your letter writers understand that you're applying for a PhD and what your research goals are.


  I was like more concentrated towards practical experience and have't had any publications.


If by "practical experience" you mean that you worked on an unsolved problem, then that counts as research. If you simply re-applied knowledge in order to learn how to become proficient in that field (e.g., you programmed a microcontroller to turn lights on and off via voice commands), then the research angle is harder to spin.  But, do the best you can to highlight on your applications why you believe you have the preparation to do quality research.