WASHINGTON — Peter Navarro, the White House trade adviser, lashed out at Beijing just ahead of a meeting between President Trump and the Chinese president, Xi Jinping, predicting that Mr. Trump would have the “courage” to reject a bad trade deal with China.

Mr. Navarro, a blunt populist who has long held unsparing views about China’s rise, suggested that reaching a trade deal would be more difficult than Mr. Trump’s recent comments would indicate, despite the intervention of Wall Street executives who have urged the president to repair relations quickly.

The United States and China have been locked in a tit-for-tat trade war that many economists believe will eventually be a drag on economic growth. The White House has placed tariffs on about $250 billion worth of Chinese imports and has threatened to tax nearly all Chinese goods if Beijing does not agree to end trade practices that harm American companies, including pressuring firms to hand over valuable technology. China has retaliated with its own tariffs and recently accused the United States of adopting a “winner takes all” approach to trade.

Mr. Xi and Mr. Trump are scheduled to meet in Buenos Aires this month during the Group of 20 conference, and the trade dispute is expected to be a central topic. Mr. Trump has repeatedly said that China wants to make a deal, and on Wednesday he said he was also hoping to reach an agreement with Beijing.