  We investigate for two-Higgs doublet models with intrinsic CP violation in
the scalar potential CP-nonconserving effects in unpolarized $\gamma \gamma
\rightarrow t \bar{t} $ for a range of neutral Higgs boson masses which
includes resonant $\varphi$ production and the subsequent decay of $\varphi
\rightarrow t \bar{t}$. The importance of taking into account, even in the
resonant case, the interference with the nonresonant background is shown.
Further, we propose and calculate three asymmetries which efficiently trace
CP-violating effects in $\gamma \gamma \rightarrow t \bar{t} $ using
semileptonic $t \bar{t}$ decays.
