Environment secretary George Eustice said the Government "can't rule out" having to reintroduce local restrictions to crush surges in infections.
While rates are dropping in Doncaster, the town still has some of the highest infection rates in the country.
But he admitted the return of last year's tiers system would be a last resort because it failed to stop the spread of the virus across the country.
On Monday, the next stage of easing of coronavirus lockdown restrictions is set to come in, with indoor mixing allowed once again.
But ministers are concerned about the emergence of 34 hotspots where the number of new cases is running at twice the national average.
In Yorkshire hospots have been identified in Doncaster, Selby, Wakefield and Kirklees.
Mr Eustice said the Government is "monitoring carefully" the emergence of new hotspots but admitted it's unsure why they've emerged.
He said: "We're doing a lot of surveillance testing, both in schools with regular testing at home, but also now in work places.
"So this does enable us to pick up these hotspots. We're not sure quite what's driving it.
"Whether it's particular variants that are taking hold there, whether it's that in certain areas people are perhaps being a bit too lax about the restrictions that remain in place.”
Asked whether ministers could bring back local restrictions in areas with very high infection rates, he replied: "We can't rule anything out.
"But our plan that's been set out by the PM, the reason we're being incredibly cautious about exiting lockdown, is we want this to be the last.
"We want to try and avoid having to get into a tiered system and regionalisation.
"We tried that last Autumn, we know in the end we had to go for a full lockdown."
He added: "We've got our confidence now in the vaccination programme - it's reducing transmission rates as well as hospitalisations and mortality, so that's got to be our focus.
"But there's always a risk and the greatest risk we have is a new variant will come in that the vaccine is less effective against."