Thaksin, who was ousted in a 2006 coup as prime minister and lives abroad to avoid jail for a corruption conviction, sits at the epicentre of Thailand's near decade-long political rupture.
His sister Yingluck was also booted out of office as premier by a controversial court ruling just before the military again seized power in May.
Thaksin is loathed by the Bangkok elite and their royalist supporters in the army and judiciary.
"Do not present news (about Thaskin) as everyone knows that he has violated the law," Prime Minister Prayut Chan-O-Cha, who also heads the military council in charge of Thailand, told reporters today.
"Please do not make us have to use laws, power or force," added Prayut, who has already imposed martial law across the kingdom and sweeping curbs on political discussions in the media and society at large.
His comments came after photographs emerged of Thaksin in China cuddling a baby panda, accompanied by his sister.
After months retreating from the limelight, Yingluck - and Thaksin - have started to creep back into public life, with Thailand's first female premier making appearances at high-profile funerals of key Shinawatra supporters, much to the consternation of the junta.
Prayut has overseen the appointment of a military-stacked National Legislative Assembly and will this week rubber-stamp the membership of a panel tasked with crafting a new constitution which is meant carve a pathway to elections in late 2015.
But critics say the purpose of the coup and the new charter is to find legal ways to checkmate the Shinawatras and dull the political voice of their northern voter bloc.