The Left party parliamentarians Annette Groth and Inge Höger, in addition to former MP Norman Paech, were aboard the Turkish ship Mavi Marmara when Israeli forces stormed the deck, killing several people and reportedly wounding dozens of others.
The three visibly shaken German politicians who arrived back in Berlin on Tuesday morning said that those on their ship had not been armed as the Israelis claim.
"The Israeli government justifies the raid because they were attacked. This is absolutely not the case," said former parliamentarian Paech, 72, wrapped in a blanket. "This was not an act of self-defence."
His comments were backed by two others on board the convoy when it was raided at dawn on Monday in international waters, MPs Inge Höger, 59, and Annette Groth, 56.
"We felt like we were in a war, like we were being kidnapped," Höger said. "We wanted to bring aid to Gaza. Nobody had a weapon."
However, video released by the Israeli military show the commandos being beaten with blunt objects and thrown overboard as they try to take control of a ship. Jerusalem says the soldiers opened fire after being attacked with clubs and knives by several activists.
"Personally I saw two and a half wooden batons that were used ... There was really nothing else. We never saw any knives," Paech said. "This was an attack in international waters on a peaceful mission ... This was a clear act of piracy."