Asensio, however, tapped in a late victor to give the defending champions victory and another precious away goal ahead of the second leg.
The Blues were humiliated by the champions at the Etihad, as they dropped to sixth place in the Premier League. UEFA will hear the case on February 28.
Should Madrid progress to the quarter-finals, Ramos would then have a clean slate for the final stretch of Europe's elite competition, which his side have monopolised since 2016.
"It's something I had in mind", Ramos told El Chiringuito. "It is not about underestimating the opponent or thinking the tie is already over".
'Ajax have had their problems of late, not least a bruising 6-2 loss at Feyenoord, yet at times here they were exhilarating, ' said the Uefa website after the game. Meanwhile, Dani Carvajal was banned by UEFA after a similar incident just last season.
Ramos could face a similar ban, though he did take to Twitter following his admission to backtrack on his statements. "We created space on the counter to break away at great pace and make the most of the pace we've got up top".
"The referee identified that Tagliafico's team-mate Dušan Tadić was in an offside position and interfering with the goalkeeper - preventing him from playing or being able to play the ball - as the header was being made".
However, after his comments sparked backlash on social media, the 32-year-old seemingly backtracked on his statements and tweeted: "I have not forced the card". "I did force the card... and I will support from the stands as a fan with the dream of being in the quarters".