China has pledged to expand its already deep economic footprint in Southeast Asia as President Xi Jinping this week embarked on his first visit to the region since taking office in March.

Following a two-day stop in Indonesia, Mr. Xi on Thursday travelled to Malaysia, where both countries hailed last month’s launch of a $1-billion port and industrial park expansion project as a sign of deepening Chinese investments in the region.

Mr. Xi arrived in Malaysia on a day when the United States announced that President Barack Obama would call off his visit this month to the country on account of the government shutdown in Washington. The White House said Mr. Obama would not travel to Malaysia and the Philippines, but would likely attend summit meetings in Brunei and Indonesia, including the APEC leaders’ meeting.

The visits by Mr. Obama and Mr. Xi come at a time of renewed focus on competing American and Chinese interests in the Asia-Pacific, following the Obama administration’s “pivot” to Asia strategy of renewing alliances.

Though China has been looking to widen investments in the region, where it is already the single biggest trading partner for many Asean countries, regional anxieties about China’s increasing assertiveness in maritime disputes have led many countries, such as the Philippines and Vietnam, to pursue closer security ties with Washington.

In an address to Indonesia’s members of Parliament — the first by a foreign leader — Mr. Xi did not appear to offer any new approach to the disputes. China has rejected calls from several Asean countries to negotiate multilaterally over the South China Sea’s waters and islands, which are being contested by more than 10 countries.