Atomic force microscopy detects forces between a scanning tip and molecules in the surface with which it is in contact. It is now widely used to characterize surface structure. In many cases it has been possible to achieve atomic resolution, and atomic force microscopy can therefore provide a very direct probe of molecular behavior at interface. We have used the molecular dynamics simulation of a Langmuir-Blodgett film to study the effect of tip shape on the observed pattern and to explore whether the structure of the adsorbate is significantly changed by the presence of the tip. Our results indicate that the presence of the tip close to the film causes compression of the adsorbate and subsequent enhancement of the translational structure of the film by the scanning tip and that the scanning results are sensitive to the tip geometry.