His words came as stricter new measures were expected to be announced for the North East of England, where cases are on the rise.
The Prime Minister said people have to be “both confident and cautious” and that it is “crucial” the country does not re-enter “some great lockdown again that stops the business from functioning”.
He told The Sun: “Christmas we want to protect, and we want everyone to have a fantastic Christmas.
“But the only way to make sure the country is able to enjoy Christmas is to be tough now.
“So if we can grip it now, stop the surge, arrest the spike, stop the second hump of the dromedary, flatten the second hump.”
People in the North East await an announcement on Thursday on new measures which are expected to come into effect from midnight.
In South Wales, a local lockdown will come into force from 6 pm on Thursday, meaning people must not enter or leave the Rhondda Cynon Taf area without a reasonable excuse.
Under new rules, licensed pubs, bars, and restaurants in the area will have to close at 11 pm – and meetings with other people indoors will not be allowed, including for extended households.
The area has the highest testing positivity rate in Wales, with the seven-day new case rate at 82.1 per 100,000 people in the area.
Newcastle upon Tyne has also seen a sharp rise in its rate, up from 51.2 to 64.1, with 194 new cases in the seven days to September 13.
There were 141 new cases in South Tyneside, up from 92 the previous week, and 198 in County Durham, a rise from 172.