The magnetic and structural properties of the pseudomorphic iron monolayer on tungsten substrate were studied within the density functional generalized gradient approximation. The existing strains originating from significant mismatch between iron and tungsten layers were determined for both magnetic and nonmagnetic systems. By studying the spectrum of surface phonons within the direct method, a strong dependence of lattice dynamics on magnetic interactions has been revealed. In the nonmagnetic state, the in-plane surface modes soften along the [001] direction and lead to surface reconstruction. The ferromagnetic interactions were found to be the crucial element in stabilizing the iron monolayer on tungsten. The mechanism enhancing the ferromagnetic polarization of the surface and the soft mode behavior are discussed on the basis of the calculated changes in the electronic density of states.