  We apply the new fall of conditions presented in the paper \cite{10} on
asymptotically flat spacetime solutions of Chern-Simons-like theories of
gravity. We show that the considered fall of conditions asymptotically solve
equations of motion of generalized minimal massive gravity. We demonstrate that
there exist two type of solutions, one of those is trivial and the others are
non-trivial. By looking at non-trivial solutions, for asymptotically flat
spacetimes in the generalized minimal massive gravity, in contrast to Einstein
gravity, cosmological parameter can be non-zero. We obtain the conserved
charges of the asymptotically flat spacetimes in generalized minimal massive
gravity, and by introducing Fourier modes we show that the asymptotic symmetry
algebra is a semidirect product of a $BMS_{3}$ algebra and two $U(1)$ current
algebras. Also we verify that the $BMS_{3}$ algebra can be obtained by a
contraction of the AdS$_3$ asymptotic symmetry algebra when the AdS$_3$ radius
tends to infinity in the flat-space limit. Finally we find energy, angular
momentum and entropy for a particular case and deduce that these quantities
satisfy the first law of flat space cosmologies.
