Speaking at a Downing Street briefing, the home secretary said: "If you do not play your part, our selfless police officers, who are out there risking their own lives... they will enforce the regulations. And I will back them to do so."
Earlier today, crime and policing minister Kit Malthouse warned police would be 'quicker' to hand out fines.
Police have been using a 'four Es' strategy during the pandemic, by engaging, explaining, encouraging and then, as a last step, enforcing lockdown measures - but Malthouse indicated that officers might move to the final 'E' more hastily.
Speaking to Sky News, he said: "If people play by the rules and they recognise the police are doing a difficult job in very challenging circumstances, and cooperate, then hopefully the four 'Es'; encourage, all that kind of stuff, before we get to enforcement, will have an effect.
"But I think you will find that the police are quicker to move to enforcement. That's certainly what they have indicated is their intention.
"Because we really, really have to recognise how severe the problem is and the fact we are in our worst position for some time."
It comes after Boris Johnson spoke to senior ministers earlier this week about whether the current rules are having an impact - and he has warned that tougher measures may be needed.
It seems the government is honing in on one exemption in particular, which allows people to meet with one other person from outside their household. This is meant to be for exercise in a public space.
Speaking to the Daily Telegraph, a source said that the exemption is currently being used as 'an excuse for people to go for a coffee in the park with their friends,' adding: "It may be we tighten up on things like that."
Masks could also be introduced in busy outdoor areas and even enclosed work spaces.
Speaking to Sky News about stricter rules, vaccine minister Nadhim Zahawi said: "This virus loves social interaction, especially this new variant - so the worst thing you can do is socialise.
"We must make sure we only go out to exercise or necessary shopping - but stay at home."
He added: "We don't want to go any tougher but we need people to behave so we can bring the virus under control while we vaccinate and hit that target mid-February.
"These rules are not boundaries to be pushed against - they're to bring the virus under control and save lives. I know it's hard and we're all social animals."Featured Image Credit: PA