A morphological and magnetic study of sub-micrometric nanostructures of a manganese oxide-based compound La_0.325Pr_0.300Ca_0.375MnO₃ is presented. Nanowires of 50 and 100 nm and tubes with external diameters of 200 and 800 nm were synthesized. Scanning electron microscopy with EDS microanalysis (SEM) and transmission electron microscopy (TEM) allowed to characterize the morphology and microstructure of these nanostructures. The walls of the nanotubes are composed of on average 40 nm grain size particles, while in nanowires the grains are much smaller, in the range between 4 and 20 nm. In both situations, the small grains present a random crystalline orientation, as it is confirmed by TEM diffraction experiments. Magnetization measurements and hysteresis loops are presented and discussed based on magnetic interaction between the grains, anisotropy considerations and reversal magnetization mechanisms.