John Cena is speaking out after his crushing defeat at the hands of Roman Reigns at SummerSlam ... saying his time in the squared circle is up for now, but promising he will be back again.
The WWE legend duked it out with the Universal Champ on Saturday ... in an epic back-and-forth match at Allegiant Stadium.
But the 16-time world champ came up short in the main event brawl, with Reigns taking the dub ... and then being confronted by Brock Lesnar right after.