MEXICO CITY — The Trump administration imposed financial sanctions on Nicaragua’s vice president, Rosario Murillo, and a top aide on Tuesday, ratcheting up pressure on the Sandinista government to end its brutal crackdown on a popular uprising.

Nicaragua has been convulsed since April, when peaceful student protests developed into a broad-based movement demanding the resignation of President Daniel Ortega and Ms. Murillo, who is his wife.

Washington has called on the Nicaraguan government to move up elections as a way out of the crisis, but Mr. Ortega has said that he will serve out his term, which ends in 2021. Early attempts at talks between the government and a coalition of opposition leaders foundered.

Over the summer, masked paramilitaries, often accompanied by the police, attacked protesters at barricades and regained control of the streets. Since then the government has rounded up and jailed opponents, charging many of them with terrorism. The Nicaraguan Center for Human Rights says that more than 320 people have been killed and more than 600 imprisoned since the unrest began.