Is a father's statement to his son, "I am not pleased with you" or "I am displeased with you" for an unconvincing reason considered an act of disobedience to parents? And is it a condition for the father to say, "I am pleased with you," in order to attain parental رضا (pleasure/approval), or is righteous conduct sufficient for honoring them?

It is incumbent upon a servant to honor their parents to the best of their ability. They are not obligated to gain the father's explicit acknowledgment of this honor. Thus, the father's statement, "I am not pleased with you," does not necessarily mean the son is disobedient. The father might command a sin or something not legally binding, and then view the son's refusal as disobedience. The ultimate consideration is the actual act of honoring, not the parents' perception of it.