Generating PDB file from electron density without force field minimization
The process of making structural models of macromolecules (the content of PDB files) is called model building, rather than generating, because it normally involves tedious manual building of the model in a graphical program such as Coot. A few programs can do automatic model building, but then the structure needs to be finished manually. Maybe this will change in the future.
All these programs have rather steep learning curve, so it's probably not what you are looking for.

The next problem is that you plan to start from an electron density map.
Assuming that the experimental method was crystallography, not Cryo-EM, the electron density map is derived from both reflection data and the model (and at the same time the model is built into the map, iteratively). So for the purpose of re-building or validation people generally use reflection data, not the map.