Replying to a question on perceptions that Beijing has not taken practical action to back-up its talk of greater reform and opening, and that the new law was accelerated mostly as a response to USA pressure, Mr Li said that opening up "is China's fundamental state policy".
The main job of the government is to ensure fair market access and enhanced market oversight to ensure these services are both safe and reliable, Li added.
Li added he hopes that Sino-U.S. negotiations will "achieve results that yield mutual interests", hours after Chinese media reported senior trade officials of the two countries made "further substantial progress" during their telephone talks on Thursday.
Washington and Beijing have been locked in a tit-for-tat tariff battle as USA presses China for an end to practices and policies it argues have given Chinese firms unfair advantages, including subsidizing of industry, limits on access for foreign companies and alleged theft of intellectual property.
China must "prevent a tide of unemployment", Li said.
He also projected the new foreign investment law approved by the NPC in the shortest possible time could be a main driver of growth in future.
As a tit-for-tat tariff escalation with the United States - worth hundreds of billions of dollars - has choked exports as well as private spending and investment at home, Li pledged to implement "strong measures" to prop up the nation's economy.
But he stopped short of providing a timetable for any reserve requirement ratio or interest rate cuts.
The law will offer better legal support to the protection and attraction of foreign investment, as well as regulate government behaviours, Li said.
In a report mapping out policy direction for this year, released on March 5, the Chinese government lowered its gross domestic product growth target to 6.0-6.5 percent for 2019 from last year's target of about 6.5 percent. Up to 100 million children in China are below six years old.
"We face many uncertainties this year, so we have to take more preparations, and we have policy space", Li said.
"We are not going for monetary easing, but trying to provide effective support to the real economy", Li said.
China will bolster its national coffers by collecting more of the profits earned by some financial institutions and centrally-owned firms, while general expenditure will be cut, Li said.
Li said the country will work to ensure employment of college graduates, whose number will reach a new high of 8.34 million this year.
The country will encourage business start-ups and innovation to create more job opportunities, he said.