Older and more establishment-aligned party officials fear the attempts at public humiliation are a political gift to Republicans eager to portray the opposition as inflaming rather than cooling passions in the nation’s capital.

“Trump’s daily lack of civility has provoked responses that are predictable but unacceptable,” Representative Nancy Pelosi of California, the House Democratic leader, said Monday, rebuking Ms. Waters, a veteran flamethrower who is enjoying something of a renaissance in the Trump era.

This sort of talk infuriates the new guard of liberal leaders, who warn that Washington Democrats risk dampening enthusiasm among anti-Trump activists if they continue denouncing direct action.

“It’s completely tone deaf to discourage this type of activity,” said Quentin James, 30, a founder of the Collective PAC, an organization dedicated to electing more African-Americans. “They’re acting as accomplices.”