China's foreign ministry said on Saturday Hong Kong matters were a Chinese internal affair and no country, organisation or individual has a right to interfere.
The comments come after Hong Kong's leader, under pressure from public protests, announced the suspension of a proposed bill that would have allowed extradition of criminal suspects to mainland China.
Ministry spokesman Geng Shuang said the ministry had taken note of Lam's announcement. He said China's determination to safeguard the country's sovereignty and security, and Hong Kong's prosperity and stability, was unshakable.
The "one country, two systems" formula under which Hong Kong has been governed by China since 1997 has been "earnestly" put into effect, and the rights and freedoms of Hong Kong people fully guaranteed, Geng Shuang said in a statement posted on the ministry's website.