A method is developed to obtain pair-potential parameters for liquids from structure factors measured by diffraction experiments. The approach is a generalization of the method of Lyubartsev and Laaksonen [Phys. Rev. E 52, 3730 (1995)]. Each step of the iterative process consists of two parts: a Monte Carlo or molecular dynamics simulation with an assumed pair-potential and the modification of the potential due the experimental data and different quantities calculated in the simulations. The choice of the structure factor as input function makes it possible to avoid the difficulties of the Fourier transformation from the inverse to the real space, to replace the solution of the set of linear equations with simple linear combination in the case of multicomponent or molecular systems, and to use least-square fit for the modification of the pair-potential. The latter is less sensitive to the errors of the data than the unique solution of linear equations applied in the original recipe. The method is tested for one-and two-component Lennard-Jones systems, and Lennard-Jones parameters for liquid argon are determined from a diffraction experiment.