The seismological analysis of Delta Scuti stars give us precise information on the stellar structure in intermediate mass stars, that is between 1.5 and 2.5 Msun. These variable stars are suitable candidates for probing some of the hydrodynamical processes, actually poorly understood, occurring in the deep interior of the stars. On the other hand, the application of stellar seismology on pulsating objects belonging to a close open cluster makes the work easier since in this case it can be considered that all the stars approximately have the same age, chemical composition and distance. In addition to this, stellar parameters like metallicity or distance are better estimated for stars belonging to a cluster than for typical field stars. We have studied a sample of six Delta Scuti stars belonging to the Pleiades cluster, observed by means of the STEPHI observational network in several intensive multi-site campaigns. Two of these campaigns were carried out during this work. The sample consists of V650 Tau, V647 Tau, V534 Tau, HD 23628, V624 Tau and HD 23194. The data analysis of three observing campaigns presented in this research, provided us with a precise information on the oscillation frequencies of the last five Delta Scuti stars, one of them hitherto considered as non pulsating star in the Pleiades cluster. The frequency oscillations of the amplitude spectrum of the time series were obtained by using two procedures: an iterative sine wave fit plus prewhitening and the PERIOD98 program. A total amount of 29 oscillation modes where detected in our sample with a significance level above 99%. We have improved the theoretical analysis suitable taken into account the rotation effect not only on stellar parameters and models but also on the oscillations eigenfrequencies, in order to obtain a better and more realistic description of the stellar structure. The theoretical oscillations eigenfrequencies were calculated taking into account the second order effect in the rotational rate for rotating models computed with the most relevant observational parameters of the cluster and of each star, namely, metallicity, distance, age and rotational velocity. The seismic stellar models were gathered together in ensembles of six, one per star, with a common distance, age, metallicity and overshooting. We have applied interpolations between theoretical frequencies, ν_{cal}, and angular rotational velocities, Ω_{rot}, in order to cover the rotation interval estimated for each stellar model. We have compared the observational frequencies with the theoretical ones at each interpolated Ω_{rot} by means of χ^{2} fitting. We have found the best mode solution by minimization of such a quantity. The requirement that the visibility coefficients of the oscillations modes depend to a large extend on the angle of inclination between rotational axis and the line of sight have been applied as a constraint of the possible mode solutions. As a result of theoretical analysis we have found possible identifications of the oscillation modes of the target stars that indicate a cluster metallicity of [Fe/H]=0.0668 (Z ˜ 0.02, Y ˜ 0.28) for an age of 70x10^{6} - 100x10^{6} years and distance modulus m_{V}-M_{V} = 5.60 - 5.70. All the stars were found to oscillate on radial and non radial p modes of low radial order. In the framework of the present theoretical analysis we have concluded that a sub-solar metallicity with high amount of He for the Pleiades cluster is unlikely, in contrast with some suggestions made for others researchers.