Using some potential theory tools and the Schauder fixed point theorem, we prove the existence and precise global behavior of positive continuous solutions for the competitive fractional system (-Delta(vertical bar D))(alpha/2)u + p(x)u(sigma)v(r) = 0, (-Delta(vertical bar D))(alpha/2)v + q(x)u(s)v(beta) = 0 in a bounded C-1,C-1-domain D in R-n (n >= 3), subject to some Dirichlet conditions, where 0 < alpha < 2, sigma, beta >= 1, s, r >= 0. The potential functions p,q are nonnegative and required to satisfy some adequate hypotheses related to the Kato class of functions K-alpha(D).