The anti-virus curbs apply to all Chinese citizens and foreigners, with no discrimination in enforcement, Cai Wei, an officer of the city's public security bureau, told a news conference, Reuters reported.
Several African countries have demanded that China tackle their concerns that Africans in Guangzhou are being mistreated and harassed amid fears the virus could spread from imported cases.
Last week, the city's US consulate said local government officials were ordering restaurants not to serve clients who appeared to be of African origin.
Anyone with "African" contacts faced mandatory virus tests followed by quarantine, regardless of recent travel history or previous isolation, it said in a statement, advising African-Americans or those who feared being targeted to stay away.