RIO DE JANEIRO, April 30 (Reuters) - Brazil's Petrobras will reduce diesel and gasoline prices at refineries by about 2% on Saturday, the state-run oil company said on Friday, the first fuel price adjustment since Chief Executive Joaquim Silva e Luna formally took charge.

The former army general replaced Roberto Castello Branco as the company's top executive earlier in April after the government apparently disagreed with the company's fuel pricing policy.

The cut came even as some experts pointed to evidence of further price pressures from increasing international oil prices.

In a note on Friday, brokerage Ativa Investimentos said its model indicated a potential 13% rise in gasoline prices.

But Petrobras said average diesel prices would fall 6 cents per liter to 2.71 reais, while gasoline prices would fall 5 cents per liter to 2.59 reais.

After landing the top job at Petrobras, Luna said he would look to avoid volatility in the domestic fuel market while not "disrespecting" international price parity.

Asked about Ativa's projection on Friday, Petrobras declined specific comment but said its prices "seek equilibrium with the international market and follow the variations in to price of the products and the exchange rate."

The Brazilian real has jumped about 4% versus the U.S. dollar over the past month.

(Reporting by Marta Nogueira in Rio de Janeiro Writing by Ana Mano and Gram Slattery Editing by Louise Heavens and Matthew Lewis)