The State Security Service said the five were trying to sell 1.6 kilos of nuclear material that included uranium-238 and uranium-235 isotopes for $3mn.
The suspects, who were arrested in the Black Sea resort of Kobuleti, were remanded in custody on Wednesday.
If convicted, they could face jail terms of up to 10 years.
Uranium enriched in the 235 isotope can be used for a nuclear bomb if it is used in a large enough quantity.
The seizures have raised questions about nuclear security in the former Soviet Union amid fears that extremists are seeking to acquire nuclear material to use in attacks.
Thursday's announcement came just 10 days after Georgia's State Security Agency said it had arrested three Georgians and three Armenians for trying to sell uranium-238.
In 2012, Armenia foiled a plot to sell another radioactive isotope, strontium-90.
In 2010, Georgia thwarted a planned sale of another radioactive substance, caesium-137.
The same year Georgian police arrested two Armenian men accused of smuggling 18 grams of highly enriched uranium from Armenia to Georgia and trying to sell it to an undercover agent posing as an Islamist extremist.
