"It wasn't bad enough, probably, for me to go down in the way that I did. I probably could have carried on and allowed the ref to pull it back afterwards if he thought there was foul play, but in that moment, whether my judgement was clouded or not, I felt like I was hit head on head, so I went down.
"I was completely entitled to. I didn't cheat the system. I didn't dive. By the letter of the law, and for our own safety, if there's a head collision, you're allowed to go down and the ref can review it."
Northampton snatched a 35-34 success against the Premiership leaders through Fin Smith's penalty with the last kick of the game.
Lawrence, 25, did not have a head injury assessment because the collision did not merit medical intervention according to data collected on the sidelines.
"I don't think I was cheating," he added.
"People say I brought the game into disrepute. I would argue that I didn't. I just went by the letter of the law. But I do apologise for that because, at the end of the day, there are a lot of kids that look up to us as players and I don't want people to think that I'm a cheat or a diver.
"I want people to play the game and enjoy it and play it in the right spirit so, like I said, I apologise for my actions in that moment. I'll leave the referee to decide if there's head contact in the future."
Lawrence was seen smiling in the aftermath when team-mate Finn Russell lined up the resulting penalty as the Franklin's Gardens crowd jeered.
"In terms of my reactions during the game, I do smile after I make a mistake," he said.
"It's something I have done my whole career. It's just my way of getting over it and moving on to the next thing. There was no wry smile or a wink or whatever people seem to think they saw.
"That's just me cracking on and getting on with the next thing. I'm probably just talking to the next person on the field next to me and making a joke at some point because, at the end of the day, I'm trying to get over it and get on to the next thing."