There is no “minimum” score required. The GRE is only one component of the application, and other factors, in particular undergraduate performance and research experience, weigh heavily in the decision. Competitive PhD applicants will have a total GRE score (from the general test) of 310 or higher (verbal and quantitative combined.) Non-US applicants, total GRE scores (from the general test) 310 (verbal and quantitative combined) are usually not competitive; applicants with these scores are encouraged to retake the GRE before applying.
MS students should have a GRE of 300 or higher.