The couples reportedly died after they were shot by their captors this week as the U.S. navy pursued their pirated yacht in an effort to negotiate their release.
Two Somali pirates were also killed and 13 others captured by the American navy after the killing of the couples.
"We condemn the actions of these and all pirates operating from our shores and we will ensure that the captured pirates are brought to justice," Somali Prime Minister Mohamed Abdullahi said in a statement.
The premier said his government "deeply regrets" the deaths of the four Americans hijacked by pirates off the coast of Somalia describing the pirates as callous men
"We are all deeply saddened by the news of these killings. Our thoughts and prayers are with their families and friends and we offer our sincere condolences," Premier Mohamed said.
He said the pirates do not represent the Somali people adding that Somalis inside and outside the country were "repulsed by this horrendous crime".
Piracy is rife along the Somali coast, the longest in Africa, as well as the Gulf of Aden. The waterway is one of the most important maritime routes in the world for commercial and military vessels.
Dozens of ships and hundreds of crew members from various countries are still being held-hostage by Somali pirates who demand huge ransoms for their release.
International naval forces patrol the seas off the war-ravaged east African country in an effort to contain the menace that has wrecked havoc on the world shipping in the region. Somalia has been without a strong central authority for the past two decades following the ouster of former ruler Mohamed Siyad Barre in 1991.