KIEV, Ukraine — The former president of Georgia who became an opposition leader in Ukraine walked free on Monday after a court in the Ukrainian capital refused to authorize his arrest, and he vowed to push for a peaceful change of government.

The sudden turn of events for the former Georgia president, Mikheil Saakashvili, came three days after his arrest on allegations that he had colluded with Ukrainian businessmen tied to Russia to topple President Petro O. Poroshenko of Ukraine, accusations that Mr. Saakashvili rejected.

“I consider myself a prisoner of Ukrainian oligarchs,” he said in what appeared to be a reference to the business background of Mr. Poroshenko, who ran a chocolate business before he was elected.

Prosecutors had asked to keep Mr. Saakashvili under house arrest, but the judge turned down the request, prompting applause by Mr. Saakashvili’s supporters.