Robles entered Wednesday's game with the score tied at 1 and got Tyler Saladino to pop out on his first pitch out of the bullpen.
Behind in the count, 3-1, to the ensuing batter, Alex Avila, Robles fired a 96-mph fastball for a strike and then walked around the mound before bending down to check on his ankle.
Robles tossed a few warmup pitches, but decided to come out of the game.
"Nothing too severe," Mets manager Terry Collins said. "He caught his spike on the rubber when he made the delivery and he was probably just a little nervous and didn't want to get in trouble at that point in the game."
Logan Verrett replaced Robles and retired Avila and Avisail Garcia before giving up the eventual winning run in the 13th.
Robles was seen in the Mets' clubhouse following the game without a noticeable limp.
Troy Provost-Heron is a reporter for MLB.com based in New York. This story was not subject to the approval of Major League Baseball or its clubs.