RSPB Cymru had urged the Welsh Government to protect the rare birds.
But the Welsh Government said it would not implement a total ban, stating there was no evidence any are currently being shot in Wales.
The world population of the birds has been declining since 1999, falling from 36,000 to 20,000.
Following a public consultation, the Welsh Government has opted to maintain the current voluntary ban on land where wildfowling clubs have specific rights to shoot.
The decision has been criticised by RSPB Cymru, who said wintering populations were at "critically low levels".
The charity said more than 160 birds would return to their regular wintering site on the Dyfi estuary in the 1990s, but numbers had dropped to 24 last year.
Director Katie-Jo Luxton said: "When a species is declining so quickly that it is under threat of extinction, you'd think the least that those in power could do is to offer it legal protection to prevent it from being shot."
In response, a Welsh Government spokesman said it was "committed to the conservation of white-fronted geese".
"We recently undertook a full public consultation which did not generate any evidence to indicate white-fronted geese are currently being shot in Wales," the spokesman said.
"The cabinet secretary therefore concluded the existing year-round voluntary moratorium is currently working effectively and is being adhered to by wildfowling clubs in Wales."
A decision not to entirely ban the shooting of white-fronted geese across Wales has been described as a "bitter disappointment".