The 28-year-old army captain said he had taken insurgents "out of the game" and operated his Apache gunship on the basis that you had to "take a life to save a life", adding that playing video games had made him "useful" with his thumbs.
Jim Murphy, the British shadow defence secretary, questioned the language Harry had used.
He said: "I'm not going to second guess whether he should or shouldn't have said it. He's obviously a young and brave man. He was candid. Perhaps he may have been more candid than the palace may have wished."
In Afghanistan, there were fears that his comments would erode relations between international forces and the local population.
President Hamid Karzai has staked his reputation on working closely with Nato-led forces and wants the US to station troops in Afghanistan beyond the end of 2014.
Sharifullah Kamawal, a member of the Afghan parliament, said Prince Harry should retract his comments, adding: "This makes the withdrawal process much faster, because for now half of the people say the foreign forces must stay for longer, but if they say these kind of things then more people will want them to go home."
Meanwhile, the Taliban were quick to capitalise on the prince's comments, saying they were an insult to the men who had fought and died alongside him. Zabihullah Mujahid, Taliban spokesman, said Prince Harry was a "coward" for only speaking only after he was out of harm's way. "This statement is not even worth condemning. It is worse than that," he said.