Blackwell, 25, has been in an induced coma and was found to have suffered a small bleed on the brain since collapsing at the end of Saturday's British middleweight title defeat by Eubank Jr.
Referee Victor Loughlin stopped the fight in the 10th round because of the horrific swelling around Blackwell's left eye, but only shortly before his father in his corner told his son to pursue Blackwell's body.
At a press conference in London on Tuesday, Eubank Jr, said: “I had spared my uppercuts. I thought this guy is hurt. I took it down a notch. I was playing.
"I’d won the fight, so I thought let’s put on a little bit of a show because people are still watching. I wasn’t throwing as many punches.”
The 26-year-old said he eased off because he knew he had “severely hurt” Blackwell.
"No fighter wants to see the man after the fight in any type of serious condition," Eubank Jr said. "I'm not going in there to damage someone, I just went in to fulfil a lifelong ambition and become British champion.
"If you watch the round, you can see me easing off.
"As fighters, we know the risks.
"We know that we are risking our health every time we step in the ring."
Eubank Sr, the former middleweight and super-middleweight world champion, added that he did tell his son to stop targeting Blackwell's head in an attempt to protect the stricken fighter from further punishment.
"Even in sparring, I tell Junior to stay away from the head because his punching is fast, powerful and dangerous," said Eubank, who left Michael Watson partially paralysed and with irreparable brain damage during their infamous 1991 fight.
"So most certainly I was saying this to protect the fighter."