  Deriving the gravitational effective action directly from exact
renormalization group is very complicated, if not impossible. Hence, to study
the effects of running gravitational coupling which tends to a non--Gaussian UV
fixed point (as it is supposed by the asymptotic safety conjecture), two steps
are usually adopted. Cutoff identification and improvement of the gravitational
coupling to the running one. As suggested in [1], a function of all independent
curvature invariants seems to be the best choice for cutoff identification of
gravitational quantum fluctuations in curved spacetime and makes the action
improvement, which saves the general covariance of theory, possible. Here, we
choose Ricci tensor square for this purpose and then the equation of motion of
improved gravitational action and its spherically symmetric vacuum solution are
obtained. Indeed, its effect on the massive particles' trajectory and the black
hole thermodynamics are studied.
