Li, speaking before starting a May 4-11 trip to Ethiopia, Nigeria, Angola and Kenya, said Chinese firms in Africa needed to abide by local laws and regulations as well as also take responsibility to protect the interests of local communities.
He said the Chinese government was willing to sit down with African countries to resolve any issues that arose between the two sides, but said theses were "isolated" cases in a relationship based on equality and mutual benefit.
"I wish to assure our African friends in all seriousness that China will never pursue a colonialist path like some countries did, or allow colonialism, which belongs to the past, to reappear in Africa," the official news agency Xinhua quoted Li as saying.
Chinese enterprises have spent heavily on infrastructure, mining and energy projects in Africa as the country seeks to expand its access to supplies of vital commodities such as oil and copper.
But in some cases, Chinese firms have been accused of treating local staff unfairly. Oil workers at two China-invested projects in Chad and Niger went on strike in March in protest against unequal pay.
In 2009, China overtook the United States as Africa's biggest trading partner, and Xinhua said more than 2,500 Chinese firms operate on the continent.
Bilateral trade between China and African countries reached $210 billion in 2013, but Beijing has been accused of holding back the continent's economic development by focusing on the pursuit of raw materials rather than the creation of local jobs and markets.
Angola, on Li's itinerary this week, has become one of China's biggest oil suppliers, with crude deliveries rising 9.9 percent to 10.66 million tonnes in the first quarter of 2014, second only to Saudi Arabia.