Argentina's navy said a "noise" picked up by sonar on Monday during the search did not come from the vessel.
Storms and high winds have limited the search for the ARA San Juan in the past several days.
The vessel, with 44 submariners on board, reported an electrical problem and was headed back to its base in the port of Mar del Plata when it disappeared last Wednesday, the navy said.
Rescuers searching for an Argentine navy submarine that went missing in the South Atlantic almost a week ago with 44 crew aboard were expected to be able to pick up the pace on Tuesday as fierce weather abated.
Under normal circumstances, the vessel has sufficient fuel, water, oil and oxygen to operate for 90 days without external help, said Balbi, and the vessel could "snorkel" - or raise a tube to the surface - "to charge batteries and draw fresh air for the crew".
Weather conditions that have hindered the search are expected to improve today, helping search teams comb a wider area, Balbi said.
Another official said earlier that the submarine reported a battery failure and was returning to base when it went missing Wednesday and lost contact with authorities. If the German-built vessel had sunk or was otherwise unable to rise to the surface since it sent its last signal, it would be winding down its seven-day oxygen supply. The vessel was submerged when the navy last made contact with it, and Tuesday marks the sixth full day of its disappearance.
ARA San Juan soon lost its communication while traversing from an Ushia, Argentina base to its Mar del Plata home base. "We welcome the help we have received to find them".
"To all the family members of the crew, and strength: these are very hard moments for them and for all of us, who are following this issue closely", Macri said.
"We analyzed these signals, which as we know were intermittent and weak", said Gabriel Galeazzi, a naval commander.
Peter Layton, a visiting fellow at the Griffith Asia Institute at Australia's Griffith University, offered a scenario similar to Balbi's: If the vessel had sunk but was still intact, Layton said, the crew would have about a week to 10 days of oxygen. Eleven boats and 10 planes from Argentina, Brazil, Chile, Peru, South Africa, Uruguay, and the United Kingdom were assisting in the search as well, Balbi said. "For now, based on the colour, they don't belong to the submarine", Balbi said. But experts later determined that neither was from the missing sub.