"We have pushed back the choice... and this will take some time depending on how long it takes the Brazilian economy to recover," Rousseff said at a joint press conference with her French counterpart François Hollande.
Brazil is looking to buy 36 multi-purpose jets to modernise its air force in a contract valued at between $4 billion and $7 billion.
The Rafale fighter, built by French firm Dassault Aviation, is up against the US aviation giant Boeing's F/A-18 Super Hornet and Swedish manufacturer Saab's Gripen.
Brazil, which boasts the world's sixth-largest economy, began considering buying a new fighter model several years ago, but Rousseff said the government had postponed making a decision in the face of a sharp economic slowdown.
The Brazilian economy rose 2.7 percent last year, sharply down from a sizzling 7.5 percent in 2010.
"We are waiting for growth at a higher rate that will permit us to make this project a priority again," said Rousseff.
She said there were signs that growth was picking up "but we still have to be careful about extraordinary expenditures".
Brazil posted 0.6 percent growth in the third quarter after stagnating with 0.1 percent growth in the first quarter and 0.2 percent in the second.
In late September, a senior Brazilian government official told AFP on condition of anonymity there would be no decision on the contract before next year.
He dismissed suggestions that Brazil, which is currently experiencing sluggish economic growth, already favoured a particular plane.
The early favourite was the Rafale, but Brasilia finds it too expensive and has been pressing for a better price. Paris has offered full technology transfers in its bid to win the contract.
Boeing's F/A-18 Super Hornet is cheaper, but Brazilian officials are wary of Washington's possible use of technology restrictions.
Hollande emphasised that France was willing to share technology in order to clinch the first foreign sale of the fighter that is the mainstay of the French airforce and was used in the NATO air campaign against former Libyan leader Muammar Qaddafi's regime.
"We have always wanted transfers," said the French president. "That is the method we have selected."
Rousseff's predecessor, Luiz Inacio Lula da Silva, publicly expressed his preference for the Rafale in 2009, but since taking office in January 2011 Rousseff has repeatedly pushed back taking a decision.