Please let us know its the Prime Minister as Shri is not always understood. Shri is a common term for respect and not exactly his job title.
Ganesh is Shri Ganesh.. but that does not mean that we consider Narendra Modi on equal footing as Ganesh.
Secondly, if you must use the local term; its Pradhanmantri as that is his title.
Pradhmantri is not his Title, that is his Post and his Role.
Pradhan = Prime, Mantri = Minister. So PradhanMantri = Prime Minister.
Shri in sanskrit indicates the goddess of Wealth and Prosperity. It later expanded to denote Respect.
The English equivalent of "shri" is "sir".
Shri is also used in Mayanmar, Nepal, Indonesia, Thailand, Sri Lanka, Malaysia. In short it is used everywhere with Indian cultural influence.
Pakistan and BD being the exception due to their "sufi" Islamic heritage
For e.g. Sri Lanka's Official capital is called "Shri Jayawardenepura Kotte"
Islamic Kingdom of Brunei has a Capital city called "Bandar Seri Begawan." This literally translates as "Port Sri Bhagwan"