UNITED NATIONS — Russia’s top diplomat said Friday that the Obama administration had been “small-hearted” and vindictive toward his country, spoiling relations and jeopardizing cooperation on critical issues including the Syria conflict.

The remarks, by Foreign Minister Sergey V. Lavrov, came during a news conference he held on the sidelines of the United Nations General Assembly.

“U.S.-Russia relations are suffering not from the fact that there are conflicts but rather because the previous U.S. administration was small-hearted and they were revengeful,” Mr. Lavrov said. “They put this time bomb in U.S.-Russia relations. I didn’t expect that from a Nobel Peace Prize winner.”

Kevin Lewis, a spokesman for former President Barack Obama, did not immediately respond to an emailed request for comment.