Provincial Governor Julien Paluku said the arrests were made Thursday after a car chase from the Goma airport.
Among those detained were two Nigerians, a Frenchman and an American who arrived aboard a Nigerian aircraft on Thursday.
Paluku said the suspects had arrived in Goma with a large sum of money to buy gold.
"This plane, which had on board four businessmen: an American, a Frenchman and two Nigerians, was sent from Abuja with the special mission of buying gold," he said.
The government banned mining and mineral trade in eastern Congo in September, trying to regularize an industry controlled by armed groups including former rebels in the national army.
Brig. Gen. Bosco Ntaganda, a former commander of a Tutsi-led rebellion in eastern Congo in 2008, was sent in September to enforce a government mining ban. Ntaganda told The Associated Press that his soldiers helped catch the suspects.
"My men collaborated with the security services to stop them," he said.
In response to allegations he'd heard that he was involved, Ntaganda said: "Never; I am a soldier, I am not a businesssman and furthermore, mining activities are prohibited on our premises."
Government spokesman Lambert Mende confirmed the arrests, but did not give more details.
"The Congolese government is determined to put an end to the mafia in the east of the country," he said.