The Blaugrana exceeded their transfer budget in the summer of 2011 following two high-profile arrivals, and Faus has stressed that they cannot afford another summer of big spending.
"Last year we surpassed our transfer budget with the signings of Cesc Fabregas and Alexis Sanchez," Faus stated in the end-of-year financial report.
"We cannot overspend our budget by €20 or 30 million each year. It would put our business plan at risk. It would not be sustainable.
"The club needs to be cautious if it is to be able to take on ambitious future projects. We have to look to the medium and long-term stability of the club. Rational and austere measures need to be applied in order to secure a positive balance sheet.
"The club must reduce the debt to sustainable levels and, above all, not take on more debt. We have to prepare for what could happen in the near future and have stronger assets. For ambitious real-estate projects, we need a healthy balance sheet."
Barcelona's current debt stands at €335m.