The Premier League leaders were 1-0 up when Real substitute Rodrygo equalised in the last minute of normal time and grabbed a second a minute later.
"We were close. We were close. But in the end we could not reach it," Guardiola told BT Sport after the prize slipped through his fingers again. "They put a lot of players in the box, with Militao, Rodrygo, Vinicius, Benzema and they put in crosses and scored two goals. The European trophy is the one the Abu Dhabi-owned club, whose sole European club trophy remains the now-defunct Cup Winners' Cup in 1970, yearn for.