We present a search for new particles which produce narrow two-jet (dijet) resonances using proton-antiproton collision data corresponding to an integrated luminosity of 1.13  fb−1 collected with the CDF II detector. The measured dijet mass spectrum is found to be consistent with next-to-leading-order perturbative QCD predictions, and no significant evidence of new particles is found. We set upper limits at the 95% confidence level on cross sections times the branching fraction for the production of new particles decaying into dijets with both jets having a rapidity magnitude |y|<1. These limits are used to determine the mass exclusions for the excited quark, axigluon, flavor-universal coloron, E6 diquark, color-octet techni-ρ, W′, and Z′.