CARACAS, Venezuela — An international summit meeting on Tuesday that was meant to break the political stalemate in Venezuela became a one-sided showcase for the United States’ toughest sanctions yet on President Nicolás Maduro’s authoritarian regime.

During the conference of more than 50 countries in Lima, Peru, the Trump administration rejected compromises proposed by international mediators and some Latin American nations as it doubled down on its so-called maximum pressure policy to oust Mr. Maduro.

Mr. Maduro’s government wasn’t invited, prompting his allies — Cuba, China, Russia and Turkey — to decline the invitation to the meeting.

“We take this step to deny Maduro access to the global financial system and to further isolate him internationally,” John R. Bolton, the administration’s national security adviser, said in Lima, outlining a freeze on Venezuelan state assets in the United States. “We want to send a message to third parties wanting to do business with the Maduro regime: There’s no need to risk your business interests in the U.S. for the purposes of profiting from a corrupt and dying government.”