The military government said in a statement on Thursday: "In order to maintain law and order, meetings of political parties and conducting of other political activities are banned.
"Political gatherings of more than five people have already been banned, but political activities can resume when normalcy is restored."
The coup leaders also confirmed the detention of four members of the toppled prime minister's administration.
The meeting bans are the latest moves by the army to tighten its grip over the country.
No open opposition has surfaced to Tuesday night's power grab, that saw Thaksin being toppled as he visited the United States to attend a meeting of the UN General Assembly.
Less than 48 hours after the army sent tanks into the streets of Bangkok, the Thai capital returned to normality with businesses reopening and roads jammed with traffic.
Caught off guard by the sudden turn of events, Thaksin lay low in London, after travelling to the city from the US.
In a statement given by an aide to reporters, Thaksin said he would take a "deserved rest", and urged the military leaders to quickly arrange for new national elections.
He also urged "all parties to find ways and means to reconcile and work toward national reconciliation for the sake of our king and country". The statement said he was planning to do possible charitable work for the country.
A prominent Thai opposition leader has meanwhile urged the military government to call elections in six months.
Abhisit Vejjajiva told Reuters: "We cannot and do not support any kind of extra-constitutional change, but it's done.
"They could make changes to the 1997 constitution and if that's case, there is no reason to take a year"
"The country has to move forward and the best way forward is for the coup leaders to quickly return power to the people and carry out reforms they promised."
Coup leader General Sonthi Boonyaratglin said on Wednesday a new civilian prime minister would be chosen in two weeks after which the generals would "step out".
But he said it would take a year to craft a new constitution to be put to a public referendum and then followed by elections.
But Abhisit, 42, who became head of Thailand's oldest party after a crushing election defeat by Thaksin in February 2005, said: "There is no need to write a brand new constitution."
Abhisit said the 1997 People's Charter constitution was basically sound, but Thaksin had exploited flaws in its checks and balances.
"They could make changes to the 1997 constitution and if that is the case, there is no reason to take a year," Abhisit said. "Six months is a good time."