The Athletics say Cespedes was scratched just before Friday night's game began because of a sore left wrist. The Angels won 4-1.
"It came up today in batting practice," A's manager Bob Melvin said. "When he was taking some swings in the cage, he still felt it, so we pulled him out."
Cespedes hit 32 homers to win the Derby on Monday night at Citi Field in New York. The left fielder from Cuba was the first non-All-Star to win the contest. The American League West-leading A's opened a three-game series in Anaheim against the Angels.
Cespedes was replaced by Chris Young, who had an RBI double to give Oakland its lone run.