  In this article we consider the motion of relativistic strings in the
Minkowski space $\textbf{R}^{1+n}$. Those surfaces are known as a timelike
minimal surface, and described by a system with $n$ nonlinear wave equations of
Born-Infeld type. By constructing a suitable Nash-Moser iteration scheme, we
prove that the $n$-dimensional relativistic strings can admit a more
generalized time quasi-periodic motion in $\textbf{R}^{1+n}$. Moreover, those
time quasi-periodic solutions are also timelike solutions.
