The rate reached 31.5% in the 12 months to March 20, which was the end of Iran's calendar year, the semi-official Mehr news agency quoted the center as saying on Monday.
Inflation was 27.4% at the end of last December, according to previously released official data. The rate was 26.4% in March 2012.
Iran has suffered double-digit inflation for most of the past decade. Inflation began rising sharply at the end of 2010 when the government slashed food and fuel subsidies;
since then the sanctions, imposed over Iran's disputed nuclear program, have pushed down its currency, adding to pressure on prices.
Analysts say that including prices of imported goods, Iran's real inflation rate may be roughly twice as high as the official number.