Xi praised Hong Kong Chief Executive Carrie Lam for holding fast to the principle of "one country, two systems," and for courage during an "extraordinary period" for Hong Kong.
Lam met with Xi and Premier Li Keqiang during her first visit to Beijing since pro-democracy candidates swept local Hong Kong elections last month in a rebuke of how her administration has handled months of fiery anti-government protests.
"In the past year, our politics, economy and society have really faced big problems," Lam said in her meeting with Li.
Hong Kong was returned to China in 1997 under a "one country, two systems" framework which promises the city more democratic rights than are allowed on the mainland. In recent years, however, the arrests of booksellers and activists have stoked fears of a growing encroachment by the ruling Communist Party.
The mass demonstrations began in June in response to proposed legislation that would have allowed Hong Kong residents to be tried for crimes in mainland China. While Lam has since withdrawn the bill, protesters have continued calling for broader democratic reforms and an independent inquiry into accusations of police brutality.
Some protesters have increasingly resorted to violence. A lull in clashes ended Sunday evening when protesters threw bricks at police officers, who in turn fired tear gas. According to the authorities, the rioters also set fires, blocked roads and smashed traffic lights with hammers.
A video showed truncheon-wielding riot officers squirting pepper spray directly at a photographer in a group of journalists and ganging up to beat him. An online media site, Mad Dog Daily, said its photographer was beaten and detained, but couldn't confirm he was the same one being beaten in the video.
That violence and scattered confrontations in shopping malls earlier Sunday, where police also squirted pepper spray and made several arrests, ended what had been a break of a couple of weeks in conflicts between police and protesters.
Police said they arrested 31 people Sunday and 99 over the past week, taking the total number arrested since June to beyond 6,100. They also said that officers fired 27 tear gas rounds on Sunday.
Protesters in Hong Kong said they don't expect Beijing leaders to ditch Lam in the foreseeable future, because that would be an embarrassment for them and hand too large a victory to the protest movement.
"If they did change, let her step down, then that means that it's a loss in the battle," protester Fong Lee, a social worker, said at a rally in Hong Kong on Sunday. "The Communist Party wouldn't do that."