\usepackage{etoolbox}
\makeatletter
\patchcmd{\@footnotetext}{\footnotesize}{\scriptsize\sffamily}{}{}
\makeatother
یا \makeatletter
\patchcmd{\@footnotetext}{\footnotesize}{\scriptsize\sffamily}{}{}
\makeatother
\usepackage{footmisc}
\renewcommand*{\footnotelayout}{\scriptsize\sffamily}
\renewcommand*{\footnotelayout}{\scriptsize\sffamily}