There should be an "urgent review" of 10pm closure times for restaurants and pubs, Greater Manchester's mayor says.
Andy Burnham said it meant people were gathering in homes and supermarkets that were "packed out to the rafters" once the bars closed.
Scenes of crowds forming after closing time have been filmed in UK cities including Liverpool and York.
There are no specific plans to review the policy, but all measures are kept under review, the PM's spokesman said.
He highlighted a police statement that said the crowds seen in Liverpool over the weekend were dispersed within minutes, with the city centre "virtually empty" by 22:30 BST.
The 22:00 closing time had been used in local lockdown areas and experience there suggested it struck "the right balance", allowing businesses to trade "for the majority of the evening", the spokesman added.
Meanwhile, Health Secretary Matt Hancock said the government is putting into law existing guidance that people from different households in the north-east of England should not mix in any indoor setting.
He said the ban was being introduced from midnight on Wednesday because a "large number" of infections were occurring in indoor venues other than people's homes - where mixing households is already banned by law.
The UK reported another 4,044 confirmed coronavirus cases in the last 24 hours. A further 13 people died within 28 days of a positive test, the government said.
Under the new restrictions, all pubs, bars and restaurants in England and Scotland must provide table service only and close by 22:00.
In Wales, all licensed premises must stop selling alcohol at the same curfew time and close 20 minutes later, at the latest.
In Northern Ireland closing time remains at 23:30, with First Minister Arlene Foster last week saying that no decision had yet been reached over imposing a curfew for pubs and restaurants.
It comes as fines of up to £10,000 for refusing to self-isolate come into force in England and thousands of students are self-isolating in university accommodation across the UK.
Mr Burnham said people gathering after closures was "the opposite of what local restrictions here are trying to do".
"My gut feeling is that this curfew is doing more harm than good," the Labour politician told BBC Radio 4's Today programme.
"I think there needs to be an urgent review of the emerging evidence from police forces across the country."
He suggested one option could be to impose a 21:00 cut-off on alcohol sales in shops to prevent the rush to off-licences after the pubs close.
Mr Burnham has also called for more financial support for areas under greater restrictions and tougher powers for local areas to close businesses not observing the rules.
Greater Manchester's night-time economy tsar Sacha Lord tweeted that the plan was "ill-thought-out" and "shambolic".
Senior Conservative MP Tobias Ellwood said the earlier closing time "makes no sense", saying figures suggested only 5% of coronavirus outbreaks were linked to hospitality.
The health secretary faced several Tory MPs in the House of Commons who criticised the way the new coronavirus regulations were introduced without Parliamentary scrutiny.
Former minister Mark Harper said laws that exposed employers and directors to serious criminal penalties should not be imposed "by decree". And Wycombe MP Steve Baker said the measures had been briefed to the media eight days in advance, suggesting there had been time for a debate.
Mr Hancock said the government had to move "at pace", but said he was looking at ways to ensure Parliament "can be properly involved in the process in advance where possible".
Liverpool's Labour mayor Joe Anderson has also spoken out about the early closures, saying they are "making things more dangerous". Crowds gathered in the city as the pubs turned out drinkers on Saturday night.
Extra restrictions on socialising between households were introduced in Greater Manchester, as well as parts of Lancashire and Yorkshire, at the end of July following a spike in cases.
John Apter, national chairman of the Police Federation, said: "My colleagues will do the best they can to encourage and coerce people to move on but it is really difficult.
"All that you need is a hostile group that turns against those officers and the resources for that city centre are swallowed up dealing with that one incident."
Health minister Helen Whately defended the policy and urged people to head home after their evenings out.
She said the government was keeping an "open mind" about the new regulations.