  We investigate the magnetic excitations in view of the recent reports
suggesting that the spin-wave energy may exhibit a significant dependence on
the in-plane strain of a thin film of La$_2$CuO$_4$. The nature of dependence,
as we find, can be explained naturally within a two-orbital model based on the
$d_{x^2-y^2}$ and $d_{3z^2-r^2}$ orbitals. In particular, as the
orbital-splitting energy between the $d_{x^2-y^2}$ and $d_{3z^2-r^2}$ orbitals
increases with compressive strain, the zone-boundary spin-wave energy hardens.
However, the hardening persists only until the orbital splitting reaches $\sim$
2eV, beyond which there is no significant change. The behavior of zone-boundary
spin-wave energy is explained in terms of the extent of hybridization between
one of the exchange-split $d_{x^2-y^2}$ band which is nearly half filled and
the $d_{3z^2-r^2}$ band. The role of second-order antiferromagnetic
superexchange process involving the inter-orbital hopping is also discussed.
