The 56-year-old, who was extradited from the UK, also told New York federal court he would give up freedom if the price was his dignity and beliefs.
Mr Hamza countered three weeks of government evidence with answers to rapid-fire questions posed by defence lawyer Joshua Dratel.
"No," he calmly replied repeatedly as Mr Dratel asked him if he participated in a December 1998 kidnapping in Yemen, tried to organise a jihad training camp in the US of Oregon, aided al Qaida or sent anyone to Afghanistan to engage in jihad training.
An indictment charges him with conspiring to do all those things. If convicted, he could face life in prison, a prospect he said he did not fear.
"If my freedom comes at the expense of my dignity and my beliefs, then I don't want it," Mr Hamza said, speaking quietly.
When Mr Dratel asked him if he gave material support to terrorists or provided the Taliban in Afghanistan any goods or services after the September 11 terrorist attacks, he said: "Never."
"Did you ever aid or abet anyone committing those offenses?" Mr Dratel asked.
Hamza responded: "Never, as far as I know."
His evidence came three weeks into the trial and minutes after the government finished its case.
Mary Quin, the government's last witness, recounted her dramatic escape in December 1998 from Islamic extremists who thought kidnapping 16 Westerners might enable them to force the release of their friends from Yemeni jails.
The trial continues.