Washington last month imposed sanctions on some of Russia's biggest companies and businessmen, including Deripaska and his aluminum empire, in response to Moscow's alleged meddling in the 2016 U.S. presidential election and other activities.

"Of course, we are not lending any new money to him, we are not having any operations with him," Kostin told CNBC, adding that VTB was waiting to see what the U.S. Treasury Department's next steps would be.

"We hope that the issue will be resolved because we are a big creditor to him," Kostin said.

"The business with newly sanctioned institutions represents less than 2 percent of our assets so of course it will affect us to a certain extent but we still have to see what's going to happen with them as there's some discussion that they could be lifted for Rural and some other companies. So we shall see, but at the moment it doesn't represent a huge problem for us," he said.

The U.S. Treasury Department on Tuesday said it would extend the deadline for U.S. customers to comply with sanctions against Deripaska's GAZ, a car maker, giving Americans until Oct. 23 instead of June 5 to wind down operations and contracts with the company.

Washington has previously offered a similar extension to sanctioned aluminum producer Rural, in which Deripaska holds a 48 percent stake.

(Writing by Polina Ivanova; editing by Jason Neely)