Addressing a meeting of representatives and executives from about 100 multinationals at a two-day China Development Forum in Beijing, Li also said China is likely to import up to $10 trillion of commodities and services in the next five years to boost domestic consumption, China Daily reported Tuesday.
Chinese policymakers want to spur domestic consumption to lessen the economy's dependence on exports, which have been adversely affected by the global economic slowdown.
In his pledge to maintain China's open policy, Li also promised a further opening up of services and industries related to energy-saving and environmental protection, the report said.
The meeting was organized to address concerns of multinational companies about the investment environment in China.
Li said the government will ensure foreign businesses fair access to the market and a level playing field.
Those attending the meeting submitted a report on how foreign businesses could help the world's second-largest economy in achieving sustainable and stable growth in the midst of the European debt crisis.
"China will expand its opening-up policy, and the nation needs to promote domestic consumption through continuing to open up its markets," Li said.
Li said China is faced with two unprecedented transformations of completing its modernization process for its 1.3 billion people and to address and implement policies relating to climate change, green development and environmental protection.
China has set a gross domestic product growth rate of 7.5 percent for this year, unchanged from last year, and Li said in order to maintain sustainable economic growth, China must rely "on domestic consumption in the long-term."