WASHINGTON—The U.S. Treasury Department on Friday imposed sanctions on Russia’s Agrosoyuz Commercial Bank, saying it handled transactions for North Korea in violation of United Nations bans.

The move advances the Trump administration’s “maximum pressure” campaign to press Pyongyang to eliminate its nuclear-weapons program, after a roughly five-month pause in Treasury designations against North Korea and its facilitators. President Trump, amid negotiations with Kim Jong Un’s regime to rid the country of its weapons of mass...