We generalize a recently proposed self-consistent nonperturbative theory for classical systems by introducing the effect of the interaction potential in the functional form of the correlation function. The theory may be relevant for colloidal systems characterized by interactions that can be expressed in terms of a hard core plus a short-ranged term, and it is applied to two- and three-dimensional systems with Yukawa interactions. The results for the correlation function are in very good agreement with simulations, which confirms the suitability of the functional form that we propose. The thermodynamic properties are also in fair agreement with the predictions obtained by simulation, and this agreement goes over to the complete phase diagram. We believe that the theory is capable of providing more reliable results than simulation in fluid regions of the phase diagram where signals of crystalization make it difficult to accurately obtain the location of the fluid-to-solid phase transition. The theoretical predictions remain accurate even at relatively low fluid densities, a region where the theory is not intended to perform well, and an explanation based on clustering effects is provided. (C) 2003 American Institute of Physics.