The First Minister for Wales has written to the prime minister urging him to impose similar travel restrictions for people living in areas with high levels of coronavirus infections in England to those in Wales.
Mark Drakeford, in a letter to Mr Johnson, said people living in such areas in England can travel long distances, potentially "spreading the virus well beyond their locality".
In Wales, people must not enter or leave areas subjected to local lockdown restrictions without a reasonable excuse such as going to work.
On Wednesday, Plaid Cymru MP Liz Saville-Roberts raised the issue with the Prime Minister directly, saying "leisure travel" from locked down areas of England to Wales "has got to stop."
Boris Johnson replied: "Overall the UK is proceeding with the same approach and I'm very grateful to Mark Drakeford and everybody else in the Welsh Government for the way we're working together to defeat the virus.
"Yes there will be some differences, and yes there will be some seeming illogicalities, that's inevitable, inevitable in tackling a pandemic."
It comes after the issue was raised in the Senedd chamber by Plaid Cymru's leader Adam Price who said there is "nothing set out in the guidelines" which stops someone from a "Covid hotspot" in England travelling to areas of Wales with low community transmission.
He said, "Many of us will have been surprised and somewhat alarmed at the scenes from the top of Snowdon over the weekend, with long queues of people attempting to reach the summit with complete disregard, it would appear, for social distancing guidelines, but it raises a wider issue."
The First Minister said he agreed that the pictures were "alarming", but there is no evidence to suggest the influx of tourists over the summer in parts of Wales caused an outbreak of Covid-19 in those areas.
"I think it's very important to be guided by the evidence and I think that that is a tribute to two things: it is because people have heard our message about, 'Visit Wales safely', and it's a tribute to the efforts that have been made in those communities to welcome people from elsewhere, which is so important to the local economy, while doing it in a way that does not cause a risk to public health".
But, Mr Drakeford did add the local lockdown restrictions which mean people cannot travel outside an area without a reasonable excuse - and going on holiday is "not one of them".
He said he has written to the prime minister urging him to do the same in England.
"I don't think it is right for us to institute a set of border controls trying to prevent people from elsewhere visiting Wales: I think that would lead us into... difficult territory.
"But I do think that as we act to prevent people who live in hotspots in Wales from travelling to England and taking the risk of the virus with them, so the Prime Minister in his capacity as the Prime Minister of England in this case ought to do the same to prevent people from English hotspots from travelling elsewhere in England to Wales or other parts of the United Kingdom because of the risk that that undoubtedly poses.
"I wrote to him yesterday asking him to do that, urging him to call a COBRA meeting for this week, as the First Minister of Scotland did at the weekend, and I look forward to a reply."
Currently, 12 out of Wales' 22 local authorities are in a local lockdown, equating to around two million people.
Restrictions means people cannot meet up with anyone indoors not from their household and are not able to leave the area without a "reasonable excuse".