The Foreign Ministry has targeted all Asean members to defend the military coup in Thailand, with Vietnam next on the list.
Foreign Ministry spokesman Sek Wannametee said on Wednesday the ministry would visit all members of the Association of Southeast Asian Nations to explain the political situation in Thailand.
Permanent secretary for foreign affairs Sihasak Phuangketkeow will meet Vietnamese officials on Thursday on the mission, the spokesman said. The country is contacting other countries in the bloc for a visit before expanding to countries outside the region, he added.
Vietnam is the second country Mr Sihasak will visit after the first stop in Myanmar on June 2.
Myanmar is the Asean chair this year.
At present, 63 countries issued travel advisories of varying degrees for their citizens planning to visit Thailand.
Italy has downgraded its warning, from urging Italians to be cautious and monitor the situation in the kingdom to recommending they avoid unnecessary visits to Thailand, the Thai ministry said.