In the stark warning, Matt Hancock said he was “reluctant” to go down the route of shutting public spaces as “people have had a pretty tough lockdown”.
But he added that if there was a spike in the number of coronavirus cases “then we will take action”.
It comes as Bournemouth, Christchurch and Poole council declared a major incident after services were “completely overstretched” as huge numbers of visitors crowded onto the beaches during the day.
Chief medical officer for England Professor Chris Whitty later urged people to follow social distancing rules in the hot weather or risk causing a spike in coronavirus.
He wrote on Twitter: “Covid-19 has gone down due to the efforts of everyone but is still in general circulation.
“If we do not follow social distancing guidance then cases will rise again.
“Naturally people will want to enjoy the sun but we need to do so in a way that is safe for all.”
Bournemouth, Christchurch and Poole council said extra police patrols had to be brought in following the “irresponsible” behaviour of crowds who gridlocked roads, dumped rubbish, abused refuse collectors and parked illegally.
Meanwhile, thousands of Liverpool fans flocked to Anfield on Thursday night to celebrate the club’s Premier League title.
Temperatures soared to 33.4C (92.12F) at Heathrow Airport in west London on Thursday, making it the hottest day of the year so far.
Meanwhile, Prime Minister Boris Johnson is expected to announce on Friday the Government’s plans for air bridges, which will allow Britons to go on holiday to certain destinations without needing to quarantine for 14 days on their return, the Telegraph reported.
The first of these air bridges will allow holidaymakers to travel to “low-risk” European destinations, including France, Italy, Spain, Greece and Germany, from July 4.
Henry Smith, Conservative chairman of the all-party Future of Aviation group, said the plan was a “welcome first step” but urged the Prime Minister to widen the bridges to the whole of the EU.
Walk-in centres for Covid-19 testing are also being set up to make it easier for people without cars to get tested for the virus.
Six centres are being trialled in Newcastle, Rochdale, Leeds, Brent, Newham and Slough, with the latter described as a hybrid drive and walk through.
The exact location of the centres has not been confirmed by officials but one is understood to be on a basketball court, and there have been reports they will spring up in empty shops and car parks.