Hamilton's Mercedes came up behind Sutil's slower Force India at the Parabolica on his final Q2 lap and had to back right off.
The race officials accepted that Sutil had not acted deliberately to halt the Briton's charge but said a penalty was due.
"The stewards determined the impeding was not intentional, however it is the responsibility of the driver to be aware of the approaching car," said an official statement.
Hamilton ended up 12th, but said he was on course for a disappointing result even before Sutil delayed him.
"It doesn't matter anyway," he said. "I should have done it on the lap before anyway."