Sirleaf said, as part of a lecture series sponsored by U.S. supermajor Chevron, that economic reform would bring investors to her country.
"Liberia is committed to openness and accountability to encourage investment by foreign oil and gas companies but in a way that increases opportunities for Liberia's people," she was quoted by energy reporting agency Rigzone as saying.
Sirleaf said more than $16 billion was invested in natural resources such as oil in the past six years. A committee is working to address potential conflicts of interest in the Liberian energy sector, she said.
"Liberians have high expectations -- the learning curve is steep -- and we are committed to getting it right to ensure long term peace, security and economic development," she was quoted as saying.
Chevron in 2010 announced that it received approval from the Liberian government to take control of a 70 percent interest in three deep-water concessions off the country's coast.
Sirleaf, awarded a share of the Nobel Peace Prize last year, won a second term in office last year after fending off a strong challenge by former diplomat Winston Tubman.