The new rules lower reserve requirements in soles to 13 percent from 14 percent, according to the state newspaper El Peruano on Friday.
The central bank has lowered reserve requirements nearly every month since May to free up funds as the economy expands at a slower pace than initially forecast.
Peru's economy likely expanded around 5 percent last year, the central bank and government have said. In 2012 the economy grew 6.3 percent.
The central bank has said that it would rather continue loosening reserve rules than lower the benchmark interest rate, as it did in November for the first time in more than four years.