\documentclass[12pt]{article}
\usepackage{amsmath}

\newenvironment{myalign}{\vspace*{-1mm} \csname align*\endcsname}{\csname endalign*\endcsname\vspace*{-1mm}}

%\usepackage{environ}
%\NewEnviron{myalign}{%
%\vspace*{-1mm}\begin{align*} \BODY \end{align*}\vspace*{-1mm}}

\begin{document}
\begin{myalign}
& test
\end{myalign}
\end{document}