One of my projects is in Github and currently it does not have any license such as MIT. Therefore, it should be considered as an Open Source project by default.
Sorry, but that's wrong. We have a clear analysis of the licence status of github code that has no explicit licence, and it's not open source in any way. If you want your code to be free you need to attach a licence to it telling people what rights they have, and what obligations they assume if they exercise those rights.
But, I wish that if anyone uses this project then he makes a reference to me and my repository as well.
Nearly every free software licence there is requires that existing copyright statements be maintained, so if having
(c) 2019 Salman Lashkarara displayed is enough for you, then pick any of the standard permissive or copyleft free licences.
If you want explicit text to be displayed, something like
This code uses libfoo by Salman Lashkarara, the original source of which can be found at https://github.com/libfoo, you still have some options. GPLv3 s7b allows "Requiring preservation of specified reasonable legal notices or author attributions". To me, a pointer to a repository is reasonable author attribution, so GPLv3 might work for you in that regard. Other licences may have similar possibilities, but note that people may be unwilling to use GPLv3 material with a section 7 requirement.
If you want more than that, you quite quickly get into the realm of advertising, and that can be both a practical and aesthetic turnoff for free software users. Your code may not get much reuse if you take this route. The old 4-clause BSD licence required that
All advertising materials mentioning features or use of this
software must display the following acknowledgement: This product
includes software developed by the University of California,
Berkeley and its contributors.
and this caused problems. According to the GPL compatibility list,
This is a lax, permissive non-copyleft free software license with a serious flaw: the “obnoxious BSD advertising clause”. The flaw is not fatal; that is, it does not render the software nonfree. But it does cause practical problems, including incompatibility with the GNU GPL.
So in short: you need a licence. The licence is where you tell people how much credit they have to give you when reusing your code, so pick it carefully.