We evaluated the activity of the aqueous fraction and the ethyl acetate fraction of Stryphnodendron adstringens against Staphylococcus aureus and proposed their mechanism of action. The antibacterial activity of S. adstringens fractions was evaluated against S. aureus and the cell targets were rated by docking. The fractions showed moderate antibacterial activity against S. aureus without toxicity on two mammalian cell lines. They also showed synergistic antibacterial activity with tannic acid. In silico assays indicated FabG, FabZ, and FabI as probable targets. The metabolic pathway for fatty acid biosynthesis in S. aureus was affected by components of S. adstringens. The synergistic effect when combining tannic acid with S.adstringens fractions suggests a natural alternative to S. aureus control.