The Stock Exchange of Thailand index ended lower while other Southeast Asian stock markets closed mixed on Monday.
MSCI's broadest index of Asia-Pacific shares outside Japan fell about 1% after a Wall Street Journal report that US President Donald Trump planned to bar many Chinese companies from investing in US technology firms and block additional technology exports to China.
Safe-haven assets such as the Japanese yen and gold saw higher bids. The yen rose about 0.4% against the dollar.
The SET index closed at 1,622.28, dropping 12.70 points or 0.78%, in trade worth 44 billion baht. Siam Commercial Bank Plc lost 3.50% to end at 124 baht, while PTT Plc remained unchanged at 48 baht.
Singapore shares fell 0.8%, extending their decline into a third session and hitting their lowest since Oct 4, 2017. Financials were the largest drags on the index, with lenders DBS Group and Oversea-Chinese Banking Corp shedding 0.9% and 1.3% respectively.
Singapore's headline inflation rate quickened more than expected in May from a year earlier, hinting that the island state may see increased inflationary pressure in the near future.
Philippine shares gave up early gains to close at their lowest in 1-1/2 years, and marked their eighth consecutive session of decline.
Industrials were the biggest drags on the index, with SM Investments Corp declining about 2.7%.
Vietnam shares ended about 0.8% higher, building on Friday's gains, as financial and real estate stocks led the charge.
"It's a modest recovery... The market looked technically oversold on Friday, while valuations are far less expensive now.
However, overall activity is well below peaks and sentiment remains fragile," said Fiachra MacCana, head of research at Ho Chi Minh Securities.
Indonesian shares rose about 0.6%, with consumer staples and financials leading the gains.
Indonesia's trade deficit narrowed to US$1.52 billion in May but was worse than expected, due to higher oil prices. The rupiah fell about 0.6% to the dollar following the news.