Balbi said that "we are continuing to look for the submarine and the 44 crewmen".
The noise was observed around the time the ARA San Juan submarine sent its last signal last week.
Concerns about the crew's fate have set off a fierce political debate in a society sharply divided between supporters of President Mauricio Macri and opposition Peronists, who have been quick to find fault with the government's response.
The ARA San Juan's last known position was in the San Jorge Gulf area, 240 nautical miles (432 kilometers) southeast of the Valdes peninsula, in the South Atlantic.
The vessel had seven days of oxygen supply, meaning the crew would be running low if it had not been able to surface.
The news was sorely received by relatives of the San Juan crew members.
Argentine officials first learned about the noise Wednesday, Balbi told reporters.
After eight days of uncertainty amid search and rescue efforts by more than a dozen countries, the relatives received word from the Argentine navy that an explosion had occurred aboard the ARA San Juan on November 15 in the area near the submarine's last known position.
The Argentine navy lost contact with the San Juan shortly after the vessel's captain reported a failure in the battery system while the sub was submerged off Argentina's South Atlantic coast, the military said.
"Here, we're talking about a singular, short, violent, non-nuclear event, consistent with an explosion", he said.A Russian plane arrived in Argentina on Friday carrying search equipment capable of reaching 6,000 meters (20,000 feet) below the sea surface, Balbi said.
On Thursday it also emerged that an worldwide nuclear test-ban body that runs a global network of listening posts created to check for secret atomic blasts detected an "unusual signal" last week, close to where the submarine went missing.
Speaking at a forum on open government in Buenos Aires, Argentine President Mauricio Macri said: "In these hard hours, I did not want to start without sending once again all my support to the families of the crew of the ARA San Juan submarine".
The sound of "an underwater impulsive event" was detected at 1:51 p.m. GMT (10:51 a.m. local time) by its underwater microphones, it said.
It's called the Comprehensive Nuclear Test-Ban Treaty Organisation, and one of its jobs is to scan the globe for signs of explosions.
Following the announcement of the apparent explosion, Mr Williamson said: "This has not just been an agonising time for Argentina, but for our whole worldwide community, and this news is truly devastating for everyone involved in this week's search and rescue operation".