The cancellation also hits a planned meeting between Bush and Prime Minister Surayud Chulanont on the sidelines of US-Asean summit. Last month Christopher Hill, assistant state secretary for East Asia and Pacific Affairs, visited Thailand and held talks with Surayud and agreed on the meeting.
Asean has been keen to set up meetings with all key major powers, including China, India, Russia and other dialogue partners.
The meeting with Bush was due to mark the 30th anniversary of US-Asean relations. Singapore will host the upcoming Asean summit, which will celebrate the group's 40th anniversary.
The meeting was agreed on at a recent visit to Washington DC by Singapore PM Lee Hsien Loong. The US considered the island a strategic partner in its global counter-terrorism strategies. Bush has met with other Asean leaders previously at Apec (Asia-Pacific Economic Cooperation forum) meetings such as the one in Busan, South Korea, in 2005.
Thai-US relations have suffered following the coup last September. US lawmakers have criticised Thailand for the military takeover and expressed concerns over the restriction of press freedom in the country.