The rules, banning households from mixing in indoor settings, affect nearly two million people and are due to come into force at midnight.
However, confusion arose over whether this included outdoor settings such as pub beer gardens.
Labour said the PM was “grossly incompetent” for not knowing the rules.
Mr Johnson was asked to clarify the rules after a junior minister was unable to do so.
When asked if people in the North East can still meet people from other households outside, such as in a pub garden, Mr Johnson said people should follow local guidance and urged them to use their common sense.
He went on to wrongly to talk about the rule of six.
“In the North East and other areas where extra tight measures have been brought in, you should follow the guidance of local authorities – but it’s six in a home, six in hospitality but, as I understand it, not six outside,” he said.
On Twitter, Mr Johnson went on to apologise and clarified that the new rules meant those in the North East “cannot meet people from different households in social settings indoors, including in pubs, restaurants and your home”.
“You should also avoid socialising with other households outside,” he added.
Earlier, when asked on BBC Radio 4’s Today programme if people could meet in pub gardens, Education Minister Gillian Keegan said: “I’m sorry I can’t clarify that.
“I don’t know the answer to that question but I’m sure they can find out the answer to that question.”
When pressed, she said: “I’m sorry I can’t answer that question.
“I’m sure there are many people who could. I don’t represent the North East.”
‘Complexity is becoming a real risk’
One of the key requirements of public health messaging is to create a clear idea of what steps people are expected to follow.
This was easier during spring’s complete lockdown than it is now when the desire to keep society open means guidance has to be nuanced and tailored more.
Devolution has meant each part of the UK is free to come up with its own versions of what should be done.
On top of that, there are the extra restrictions imposed on local areas with high rates of infection.
It is understandable that these are tailored to local circumstances and therefore vary from place to place.
But the more complicated and intricate the rules become, the more chance the public simply switches off.
Advisers have already warned ministers publicly and privately that this is becoming a real risk alongside the problems of actually enforcing the rules in the first place.
But, as with so much with the pandemic, the problem is easy to identify – the solution less so.
People who break a new law banning households from mixing indoors in north-east England, including in pubs, will be fined.
Mixing with other households in pub gardens or outdoor restaurant spaces will not be illegal, but goes against advice, the Department for Health and Social Care has said.
Labour deputy leader Angela Rayner said the government “needs to get a grip”, saying: “These new restrictions are due to come into force across huge parts of the country tonight.”
About two million people in Newcastle, Northumberland, Gateshead, North Tyneside, South Tyneside, Sunderland and the County Durham council area have already been advised to avoid mixing.
But the new rules will come into force from Wednesday.
For those over 18 it will be £200 for a first offence, but halved if paid within 14 days.
A second offence will incur a £400 fine, which then doubles for each subsequent offence – up to a maximum of £6,400.
But Newcastle Council leader Nick Forbes said a lack of detail about the measures had led to “confusion”.
Mr Forbes said having a “gap between what’s announced in headlines and the details that people can understand” undermined the “principle of community consent”.
“What that does is sow confusion, it creates doubt, it creates uncertainty,” he added.
In areas not covered by extra restrictions in England, the rule of six – meaning social gatherings are limited to six people – applies in private homes, indoors and outdoors, and places such as pubs, restaurants, cafes and public outdoor spaces.
Source:BBC News – UK