\documentclass[a4paper,12pt]{report}

\usepackage[utf8]{inputenc}
\usepackage[round]{natbib}

\usepackage{xepersian}

\settextfont[Scale=1.1]{XB Yas}
\setdigitfont{XB Yas}

\include{chap2}

\renewcommand{\bibname}{مراجع}
\bibliographystyle{plainnat }
\bibliography{MyReferences}

\end{document}