Ramos was booked during Madrid's 2-1 win in the last-16 first leg on Wednesday, leading to a suspension.
The defender appeared to initially admit he deliberately earned the caution so he could serve the ban before the quarter-finals – should Madrid advance – before backtracking, but UEFA has opened an investigation into his comments.
Ramos said he was shocked by the uproar since the game, insisting he was initially talking about the foul – not the yellow card.
"I meant to force the foul, a foul that was inevitable; not to force the suspension."
Making his 600th appearance for the club, Ramos was booked late in the game for a foul on Ajax striker Kasper Dolberg.
The 32-year-old said he knew he would be suspended, but added it was a foul he had to commit.
"I had no choice. It was a very dangerous counter-attack in the 88th minute with the match wide open and the tie as well," Ramos said.
"That's why I said that I'd be lying if I said that I didn't know that I would be suspended, just as I knew that I had no choice but to make the foul.
"And that's what I meant when I said that in football you have to make difficult decisions."
Los Blancos are chasing a record fourth successive Champions League title this season, and are in pole position to advance to the quarter-finals following their win in Amsterdam, following a controversially VAR-disallowed Ajax goal with the game scoreless.