Cameron (31) lasted just one and a bit rounds in Hamilton on Saturday night as Tua unleashed his intimidating punching power.
While Tua (37) can look forward to the prospect of a shot at a world title, Cameron, who was ranked No 7 by the World Boxing Organisation, knows he has suffered a huge setback.
"We're at the bottom of the heap now, so it's time to climb our way to the top," he said.
"It was a hard loss. I came into this fight confident I was going to win but David caught me good in the first round and I never recovered."
Despite the manner of his defeat, Cameron still has not given up on his dream of one day challenging for a world belt.
"Hopefully, I can move forward and fight for the title," he said.
"I'm certainly not counting me out. I'm still here.
"I'm ready to go and I'll do what needs to be done."
Cameron said he had been able to come back from his one other defeat, a final-round technical knockout against Nigerian Friday Ahunanya in Auckland in November, 2007.
After that upset loss, Cameron strung together four consecutive wins before facing Tua.
Against the "Tuamanator", Cameron was knocked down twice in the opening round.
Referee Bruce McTavish, from the Philippines, finally stopped the contest seven seconds into the second round after Tua was throwing unanswered punches at will.
The TKO result means Cameron has a mandatory three-month stand-down period before he can fight again.
He was due to have some down-time anyway, to remove titanium plates inserted in his right hand after he aggravated an injury on his way to stopping Robert Davis in Gisborne in March.
Cameron defended the decision of manager Ken Reinsfield and others in his corner to let him back out for the second round.
"Kenny asked me some questions and I answered them fine," he said.
"I'm a warrior, a fighter. I don't give in to nothing. If I have to go out, I go out."
Cameron was taken to hospital after the bout as a precaution. He was checked over, was given the all-clear and returned to his hotel.
Three days after the fight, he said he felt all right.
Cameron revealed he had received a text message from Tua's wife, Robina, yesterday.
"It was just a text of support from David and Robina."
"They said they respect me highly and they wish me all the best and hope I keep going and stay in the fight game. No hard feelings, basically."
He texted back to say there were no hard feelings on his part and he thanked them for their support.
While the fighters traded verbal blows in the build-up, Cameron said it was all part of the boxing and he described Tua as "a tremendous man and a tremendous champion".
"He was victorious and he was very sportsmanlike, definitely. I totally respect what he has done. Hopefully he can go and do the business and fight for the world title."
