In response to the bombing that killed 20 people and injured 150 others, the ministry informed cabinet ministers that 35 countries had warned their citizens about trips to Thailand, the Bangkok Post reported.
Most of them issued travel alerts of levels 1-3 to encourage their citizens to take precautions during their visits to Thailand. Hong Kong, Taiwan and Slovakia gave level-4 travel advisories, asking the people not to visit Thailand unless urgent.
The Tourism Authority of Thailand (TAT) reported that people from China, Singapore, Japan, South Korea, Hong Kong and Vietnam cancelled their visits in August and September.
About half the reservations if air tickets for trips between August 18 to November 30 were also cancelled.
The TAT expected severe impacts in August and September and hoped tourism would improve in the last quarter of 2015.
However, authorities are set to launch new tourism advertisements, online campaigns and festivals to attract visitors in the remaining months of 2015.