Foreign Ministry spokesperson Geng Shuang accused the G7 - a group comprising the world's seven most developed countries - of interfering with Hong Kong's affairs and said that the issue was China's internal matter.
"No one other than the Hong Kong citizens and other Chinese people care more for Hong Kong's prosperity and stability and we can handle our own affairs well," Geng said. "I would like to advise the G7 members to stop minding others' business with ill intentions."
"The ultimate goal of the Sino-British Joint Declaration is to ensure that China takes back Hong Kong and resumes sovereignty over Hong Kong," he was quoted as saying by Efe news.
"After its return to the motherland, the Chinese government governs Hong Kong based on our Constitution and basic law. According to international law and basic norms governing international affairs, no country or organization shall interfere," the spokesman added.
Since June, Hong Kong has been in the throes of its worst political crisis in decades, sparked by a now-shelved extradition bill that would have enabled fugitives to be extradited from Hong Kong to mainland China to face trials under Beijing's judicial system.
Though the proposed law has been declared "dead" by Lam, the anti-extradition bill campaign has morphed into a broader movement seeking to reverse a general decline in freedoms and investigate alleged police brutality and violations of law.
The statement containing the conclusions of the G7 summit, held in Biarritz between Saturday and Monday, underlined the existence and importance of the 1984 Chinese-British declaration on Hong Kong and called on parties to avoid violence.
The 1984 agreement laid the groundwork for the return of Hong Kong, which took place in 1997, under which China committed to respecting the city's autonomy under the model known as "one country, two systems" for 50 years.
However, after weeks of demonstrations in the autonomous city, the Chinese government claimed that the rights and obligations recognized in the agreement are already covered under the Hong Kong Basic Law.
Hence, the Chinese authorities said they rejected all interference from any foreign country, especially the UK and the US, in the affairs of Hong Kong.
( With inputs from IANS )