The clubs held talks prior to the transfer window closing, however Betis wanted a higher figure to part company with Molina.
"In the past week, I have presented offers to Betis, but they didn't get back to me until the weekend," confirmed Sevilliano to the Daily Record.
"On Monday, Celtic increased the money and there were negotiations.
"Their offer was interesting to Jorge, but it wasn't up to the player. It was down to Betis wanting more money."