سلام
بستهٔ subcaption
رو هم بایستی فراخوانی کنین.
\documentclass[12pt]{report}
\usepackage{subcaption}
\usepackage{xepersian}
\settextfont{Amiri} % This font have been installed with tex distribution
\begin{document}
\begin{table}[!htb]
\begin{subtable}[h]{0.45\textwidth}
\centering
\begin{tabular}{l | l | l}
Day & Max Temp & Min Temp \\
\hline \hline
Mon & 20 & 13\\
Tue & 22 & 14\\
Wed & 23 & 12\\
Thurs & 25 & 13\\
Fri & 18 & 7\\
Sat & 15 & 13\\
Sun & 20 & 13
\end{tabular}
\caption{First Week}
\label{tab:week1}
\end{subtable}
\hfill
\begin{subtable}[h]{0.45\textwidth}
\centering
\begin{tabular}{l | l | l}
Day & Max Temp & Min Temp \\
\hline \hline
Mon & 17 & 11\\
Tue & 16 & 10\\
Wed & 14 & 8\\
Thurs & 12 & 5\\
Fri & 15 & 7\\
Sat & 16 & 12\\
Sun & 15 & 9
\end{tabular}
\caption{Second Week}
\label{tab:week2}
\end{subtable}
\caption{Max and min temps recorded in the first two weeks of July}
\label{tab:temps}
\end{table}
\end{document}