Not necessarily. When a solute ("A") is dissolved in a fixed amount of solvent, and another solute ("B") is added, the solvation shells around A can easily be disrupted by solvation shell formation around B. This would lead to the partial precipitation of A. The degree of precipitation depends on the amount of B added, temperature changes (the dissolution of B might be endothermic, lowering the temperature of the system, or exothermic which would increase the temp (and dissolution capability) of the system), and intermolecular interactions between A and B.
This is not necessarily indicative of denaturation of the precipitated protein.