It's unclear whether Inter are willing to take the bid into consideration, while Motta's reported 3m a year wages and his desire to stay in Milan may also prove to be a stumbling block for Zenit.
"He has two years still to run on his contract and, as far as we are concerned, he is not leaving," agent Dario Canovi recently told TMW. "He wants to stay.
"Inter have yet to tell us of their intentions with regard to whether or not they want to renew his contract.
"He is happy at Inter and is ready to remain even until his present agreement runs out. The club just have to tell us what they want."