We report on the successful trapping and patterning of micro- and nanometric particles on the surface of LiNbO3 optical waveguides via photovoltaic tweezers. A waveguide configuration is used for the first time combined with this recently proposed technique. The electric field pattern is generated by light propagating in the waveguide, allowing us to separate the light channel with the region in which particles are deposited. Results on micro- and nanoparticle trapping, by two different deposition methods on two types of planar waveguides (by soft proton exchanged and by swift heavy ion irradiation), and using single-beam and two-beam interferometric configuration, are presented and discussed.