The influence of a STM tip on the growth of nanowires deposited on step surfaces has been studied through a kinetic Monte Carlo (KMC) approach. In this work, the tip acts as a repulsive sweep for the adsorbates. It is shown that the tip can improve the nanowire distributions depending on its motion (parallel or perpendicular to the step) and its number of crossings. This improvement is restricted to a temperature range where both diffusion and tip favor the step coating.