\documentclass{article}
\usepackage{makeidx}
\makeindex
\usepackage{xepersian}
\settextfont[Scale=1.1]{XB Niloofar}
\makeatletter
\renewcommand\printindex{\newpage%
\immediate\closeout\@indexfile
\immediate\write18{xindy -L persian -C utf8 -M texindy \jobname.idx}
\@input@{\jobname.ind}}
\makeatother
\begin{document}
پر
\index{پر}
\newpage
پر
\index{پر}
\newpage
پر
\index{پر}
\printindex
\end{document}