We study how the surface states in the strong topological insulator Bi2Se3 are influenced by finite size effects and compare our results with those recently obtained for two-dimensional topological insulator HgTe. We demonstrate two important distinctions: (i) contrary to HgTe, the surface states in Bi2Se3 display a remarkable robustness towards decreasing the width L down to a few nm thus ensuring that the topological surface states remain intact and (ii) the gapping due to the hybridization of the surface states features an oscillating exponential decay as a function of L in Bi2Se3 in sharp contrast to HgTe. Our findings suggest that Bi2Se3 is suitable for nanoscale applications in quantum computing or spintronics. Also, we propose a way to experimentally detect both of the predicted effects.