We report on a search for narrow-width particles decaying to a top and antitop quark pair. The data set used in the analysis corresponds to an integrated luminosity of 680 pb(-1) collected with the Collider Detector at Fermilab in run II. We present 95% confidence level upper limits on the cross section times branching ratio. Assuming a specific top-color-assisted technicolor production model, the leptophobic Z(') with width Gamma(Z)' =0.012M(Z)', we exclude the mass range M(Z)' < 725 GeV/c(2) at the 95% confidence level.
