The Dmitrii Donskoi was part of a Russian Imperial Navy force fighting against Japanese in the 1905 war between the two nations.
Shinil Group told CNN it believes the ship and its contents are worth 1 billion won ($884,000), but was unclear about the exact value of the gold on board. Jeil also said it has "no relation to the treasure ship business".
The company said in a statement: "We spotted things that look like treasure boxes, but we have not opened them yet".
But after people began speculating on the stock market, South Korea's financial supervisory service warned it is looking for evidence of investors being misled.
The Shinil Group says its divers are certain they've found the Dmitri Donskoi, which sank in off an eastern Korean island in 1905 during the Russo-Korean war.
Russian scholars have said in the past that Russia was unlikely to put so much gold on a single ship and that it must have been much safer to move it by train.
A Russian warship from the early 1900s has been discovered off the South Korea coast by a group of explorers.
At least 60 crew members died and 120 more were wounded, with the survivors escaping to nearby Ulleungdo Island off the South Korean coast where they sunk the ship.
An official at the Pohang Regional Office of Oceans and Fisheries, which has authority on Shinil's case, said it hasn't formally discussed the company's claim because Shinil has yet to submit a request to seek a salvage right.
The warning came with Shinil Group reportedly selling virtual coins to investors, promising huge returns after salvaging the ship, which it said was at a depth of more than 426 metres.
He said the company will unveil details about what it has found in the boxes at a press conference next week, and it plans to contract a Chinese salvage company to recover the wreck.
'Investors should beware because it's uncertain whether the ship is salvageable and whether Shinil would be able to gain ownership of the assets even if it gets permission to raise it, ' said the official.
A South Korean Financial Ministry official responsible for the issue said that Russian Federation may be able to claim ownership.