Chinese President Xi Jinping attempted to play down tensions between the nations during a meeting with Vietnamese special envoy Le Hong Anh on Wednesday.

"A neighboring nation cannot be moved, and it is in the common interests of both countries to be friendly to each other," said Mr. Xi, according to an account by China's Foreign Ministry.

Vietnam's Foreign Ministry said in a statement that the countries agreed to avoid actions in the South China Sea that would heighten tensions as they seek lasting agreements that would help to resolve the maritime row.

Relations between the neighboring nations had been strained since May, when a Chinese oil rig appeared unannounced in waters claimed by both countries to explore for oil and gas. The move drew criticism from Vietnam, which dispatched government vessels to confront the rig, leading to a series of ramming incidents between Chinese and Vietnamese vessels.

The two-month standoff marked the sharpest deterioration of China-Vietnam relations in years. Washington has criticized Beijing's actions as provocative. China has described the deployment of the rig as a normal business activity on the part of one of its companies.

It remains to be seen whether Mr. Xi's remarks mean China will slow its South China Sea push. China claims nearly the entire sea as historical waters, an assertion that brings it into conflict with neighbors such as Vietnam and the Philippines. Along with China, five other governments claim parts of the South China Sea.

That Mr. Xi, China's top leader, met the Vietnamese envoy illustrates the high level of attention top Chinese leaders are paying to its disputes in the South China Sea, said Ian Storey, an expert on Asian security issues at the Institute of Southeast Asian Studies in Singapore. However, that doesn't mean China will back down in its claims.

"China has made no concessions," he said.

Since Mr. Xi took over as China's top leader in late 2012, China's central government has embarked on a series of steps to establish control over its periphery, measures that have increased tensions with neighbors and the U.S. China set up a new air-defense zone over the East China Sea in November 2013, in waters also claimed by Japan, and has stepped up land reclamation and building work on disputed islands of the South China Sea, among other efforts.

Mr. Storey said the message from China's central government has been consistent. China is willing to work together with neighbors "but we will not compromise our sovereignty claims," he said.

Diplomats in Beijing are concerned by China's moves, with some questioning Mr. Xi's pledges to improve China's relations with neighbors and the government's efforts to assert control over disputed areas.

The disputes between Hanoi and Beijing over the South China Sea, known as the East Sea in Vietnam, stretch back decades, and a single visit won't resolve underlying disputes, said Tran Cong Truc, the former chief of Vietnam's government border committee.

China's intention to control the sea hasn't changed, Mr. Truc said, and its government "will take more unilateral actions that may cause tensions in the future."

The rig at the center of the latest dispute, HYSY 981, is controlled by China National Offshore Oil Corp., the country's main state-controlled offshore oil producer. The rig was operating in waters around the disputed Paracel Islands chain, which is claimed by both China and Vietnam.

The rig was removed from the disputed waters in mid-July after Cnooc said it had completed drilling and exploration in the waters around Triton Island, or Zhongjian Island in Chinese, which is part of the Paracels chain.

The dispute over the rig led to deadly riots in Vietnam and attacks against Chinese businesses. At least three Chinese nationals were killed in the violence, and Chinese and other foreign factories were looted and burned.

By Brian Spegele - The Wall Street Journal - August 28, 2014