SYDNEY, Australia — President Xi Jinping of China and Vice President Mike Pence pushed back against criticism of each of their countries’ trade practices in speeches on Saturday at an Asia-Pacific trade summit meeting in Papua New Guinea, while seeking to assure allies of their commitment to the region.

Mr. Xi and Mr. Pence spoke ahead of what is likely to be a tense meeting between President Trump and the Chinese leader at the Group of 20 conference in Argentina later this month, where they will attempt to defuse a trade war.

Mr. Xi may also be looking to shore up ties with an important trading partner, North Korea. He told President Moon Jae-in of South Korea on the sidelines of the trade forum that he was considering visiting the North after its leader, Kim Jong-un, extended an invitation, according to a spokesman for Mr. Moon.

The Trump administration has accused China of unfair trade practices, including restricting market access, pushing American companies to hand over valuable technology and engaging in cyberespionage and intellectual property theft. It has put tariffs on hundreds of billions of dollars worth of Chinese goods; China has retaliated with tariffs of its own.