National Parks in the UK aim to conserve the natural beauty, wildlife and cultural heritage of the area they cover, and promote their sustainable use.
Three exist in Wales, each administered by their own park authority that also oversees planning applications in their areas.
Davies made the decision as the park would have been in the Senedd constituency of Rural Resilience Minister Llyr Gruffydd, who had also publicly opposed the park.
The decision follows an exercise by Natural Resources Wales (NRW), which concluded that the area satisfied the test for establishing a park.
Davies said a “significant volume of evidence” had been gathered since NRW conducted the exercise, with “strong feelings in favour and strong feelings against”.
He said potential benefits had been highlighted, such as enhancing nature recovery, strengthening climate resilience, and supporting recreation and sustainable tourism.
But important questions had also been raised about affordability, value for money, and “potential impacts on local communities, infrastructure, energy developments, housing and the Welsh language”.
He said he had given a “provisional view” and he encouraged interested individuals and organisations to submit views via e-mail or through the post.