But he says if Wales does bring in its own ban, he won't be lining the English/North Welsh border with patrol cars.
North Wales Police and Crime Commissioner Arfon Jones spoke out after Wales’ First Minister Mark Drakeford threatened a travel ban if Mr Johnson does not impose his own.
The UK government announced yesterday it will advise against non-essential travel from Merseyside.
But it stopped short of making it illegal.
Mr Jones said: “The Prime Minister is once again behaving irresponsibly and recklessly in allowing people from Covid-18 hotspots to potentially import and spread the virus here in North Wales.
“People who live in Conwy cannot leave the county, but people from hotspots like Liverpool, Manchester and Nottingham can travel into Conwy and spend time there.
“Policing is between a rock and a hard place on this issue.
'Very difficult for police to enforce'
"It is right in principle to do what Mr Drakeford is suggesting, but it is very difficult for police to enforce it, even though we’ve had more money to enforce Covid-19 regulations.
“If the Welsh Government does ban people from crossing the border into Wales from England we will do our best, along with our partners in local authorities and health to enforce the regulations.
“We’d need to look at how we would enforce these rules and have a conversation with our four chief constables here in Wales.
“I can’t see us lining the border with patrol cars because none of the police forces in Wales have the resources to do that.
“The demand now is as high as it was before the first Covid-19 lockdown.
"We will try to encourage and educate but if that doesn’t work, we will enforce."