Police broke into the Zolotoy Slon (Golden Elephant) restaurant while checking out intelligence of a planned meeting of Georgian crime group leaders, the spokesman said.
He said police detained a Georgian crime boss after he produced forged documents identifying himself as a Ukrainian citizen. The detainee was later released on a written pledge not to leave Moscow.
If found guilty, he faces a fine of up to 20,000 rubles ($750), or 180-240 hours of public service, or up to six months in prison.
Two other Georgian nationals were detained in the Moscow Region earlier Thursday on suspicion of forging temporary residence registration papers, local police said.
It is not unusual for Russian police to detain people from the Caucasus area - millions flood into Moscow from the former "southern" Soviet republics in search of work every year - but news of the detention came a day after President Vladimir Putin called for a review of immigration laws in the wake of an acrimonious spat with Georgia over an alleged espionage affair.
Experts say about one-fifth of Georgia's 4.4 million people work and earn money in Russia, about 300,000 of them illegally, according to the speaker of Russia's lower house of parliament.
"According to last year's data, $350 million was taken [by Georgian immigrants] out of Russia officially, but according to unofficial data the sum totals about $1 billion," Borys Gryzlov said Wednesday.
Moscow's authorities also raided gambling outlets this week, resulting in the closure of at least three casinos allegedly owned by the Georgian mafia, each of which earned around $1 million daily.
