The federal government is scaling back its relationship with Thailand over ''grave concerns'' about the army coup.

Months of anti-government protests and political unrest in Thailand culminated in a military coup on May 22.

In a joint statement, Defence Minister David Johnston and Foreign Affairs Minister Julie Bishop said Australia was reducing its engagement and interaction with the Thai military and would not allow coup leaders into Australia.

''Australia has postponed three activities planned for coming weeks in Thailand: a military operations law training course for Thai military officers; a reconnaissance visit for a counter-improvised explosive device training exercise; and a reconnaissance visit for a counterterrorism training exercise,'' the statement said.

''We will continue to review defence and other bilateral activities.

''The Australian government has also put in place a mechanism to prevent the leaders of the coup from travelling to Australia.

''[It] continues to call on the military to set a pathway for a return to democracy and the rule of law as soon as possible.''

Australians in or travelling to Thailand are advised to register at www.smartraveller.gov.au.