Kieswetter, born in Johannesburg to a Scottish mother, does not qualify for England until February, but has already been called up to the national performance squad after impressing in county cricket.
England already have four South Africa-born players in their squad, with Kevin Pietersen and Jonathan Trott both wearing the Three Lions in the land of their birth on the current tour, while Matt Prior and Andrew Strauss were born in South Africa before leaving for England at a young age.
Proteas captain Smith this week called on Kieswetter to pledge himself to South Africa, but the 21-year-old has been quick to restate his commitment to England.
"It is very flattering to hear someone of Graeme Smith's stature speak so highly of me but I remain committed to playing international cricket for England and that remains my ambition," Kieswetter told Somerset's website.
Somerset's director of cricket, Brian Rose, welcomed the news, adding: "He's a very exciting prospect and everyone at Somerset, from the players to the members and the supporters, will be delighted he remains committed to helping Somerset achieve further success and hopefully go on to play for England."