This Cabo da Roca guide offers three options: a badger, an Egyptian mongoose, or a weasel.
Badger is quite big and, according to East Surrey Badger Protection Society, "The front paws of an adult badger range from about 4.5 cm to 6.5 cm across for a large boar". The print is also different - see, for example, here.
As for mongoose - I couldn't find any proper image of Egyptian mongoose footprint but this one. The book "A field guide to the animal tracks of Southern Africa" does have a bunch of other mongoose species' footprints and these are always 4 front fingers and, sometimes, the 5th finger that's located to the side, while footprints in question are more like 3 + 2 pattern.
From pestdetective, this is what weasel tracks look like:
And a weasel track in a sand dune:
taken from bear-tracker.com
These footprints do seem similar to the ones in question, so I'd suggest that the answer is:
the tracks belong to a weasel or, since it is hard to be sure, to a Mustelidae family member.