Due to an inconsistent season, it's been suggested in the Spanish press Barca are ready to invite offers for the former Liverpool star.
But Bartomeu insists the money invested in signing Coutinho - which was a fee rising to €140m - means they are determined to make the deal work.
He explained: "Coutinho saw a more difficult period but I am sure that in a few weeks we will see him better.
"Against Sevilla he was at a great level. His arrival is a serious bet, a high investment and we trust him."