Musk -- one of the world's richest people -- arrived in China earlier the same day on his second trip in less than a year to the world's biggest market for electric vehicles.
Chinese state broadcaster CCTV said that during their meeting, Li had promised the country would do more to help foreign firms.
"China's very large-scale market will always be open to foreign-funded firms," Li was quoted as saying.
"China will stick to its word and will continue working hard to expand market access and strengthen service guarantees."
Beijing would also provide foreign companies with "a better business environment" so "that firms from all over the world can have peace of mind while investing in China", Li added.
Musk has extensive business interests in China and his most recent visit was in May and June of last year.
Tesla did not respond to AFP's requests for confirmation of Musk's visit, or share his itinerary for the trip.
CCTV quoted him as praising the "hardworking and intelligent Chinese team" at his Tesla Gigafactory in Shanghai during his meeting with Li.
"Tesla is willing to take the next step in deepening cooperation with China to achieve more win-win results," Musk reportedly added.
Earlier in the day, the billionaire met with the head of the China Council for the Promotion of International Trade, Ren Hongbin, "to discuss next steps in cooperation and other topics", CCTV said.
The mercurial magnate is a controversial figure in the West, but in China, Tesla's electric vehicles have become a staple of middle-class urban life.
- 'The future' -
Having once derided Chinese EVs, Musk described their manufacturers this year as being "the most competitive car companies in the world".
"It's good to see electric vehicles making progress in China," he was quoted as saying by a state-backed media outlet on Sunday.
"All cars will be electric in the future."
Musk's own company has run into trouble in the world's second-largest economy: in January, Tesla recalled more than 1.6 million electric vehicles in China to fix their steering software.
His arrival in China coincides with a cut-throat price war between firms desperate to get ahead in the fiercely competitive EV market.
China's local car giant BYD -- "Build Your Dreams" -- beat out Tesla in last year's fourth quarter to become the world's top seller of EVs.
Tesla reclaimed that title in the first quarter of this year, but BYD remains firmly on top in its home market.
His visit also comes as Beijing hosts a massive auto show, which held press events from Thursday and opened to the public over the weekend.
Comments under posts about Musk's arrival on the social media site Weibo were full of speculation that the celebrity tycoon would attend Auto China while in Beijing.
One user suggested Musk's visit was motivated by a desire to test drive an SU7, the first car model released earlier this year by Chinese consumer tech giant Xiaomi.
Xiaomi's entrance into the competitive EV sector appears to be off to a positive start, with CEO Lei Jun saying this month that pre-orders had outpaced expectations by three to five times.
Other commenters responded to reports that Musk's trip was intended to give him an opportunity to talk with Chinese officials about the possibility of bringing Tesla's Full Self-Driving (FSD) technology to the local market.
"FSD is Tesla's last hope for saving its domestic sales," one Weibo user said.
Musk's interests in China have long raised eyebrows in Washington, with President Joe Biden saying in November 2022 that his links to foreign countries were "worthy" of scrutiny.
The tycoon has also caused controversy by suggesting the self-ruled island of Taiwan should become part of China -- a stance that was welcomed by Chinese officials but deeply angered Taipei.
