Casseres scored with a strong finish on a set piece in the opening moments. Andres Reyes headed the ball to Casseres, who finished the play with a right-footed shot from close range in the center of the box.
The Red Bulls are 5-0-2 in their past seven matches since a 2-1 loss at the Columbus Crew on Sept. 14. They also are 6-2-3 in their past 11 after a 1-5-4 skid that put their 12th straight postseason appearance in jeopardy.
With five games left, the Red Bulls moved into a tie for eighth with NYCFC. The rivals are one point behind CF Montreal for the final playoff spot in the Eastern Conference.
NYCFC have gone scoreless since Valentin Castellanos struck in the 31st minute of a 1-1 draw with the Red Bulls in Harrison, N.J. on Sept. 22. Sunday's defeat saw the side's record fall to 3-6-5 in their past 16 matches, a stretch that includes an 0-2-1 mark in the Hudson River derby.
NYCFC held possession for 62.7% of the match and mustered two shots on goal. They nearly tied the game in the 81st minute when Malte Amundsen's long shot caromed off the crossbar.
Red Bulls goalkeeper Carlos Coronel made two saves for his 12th career clean sheet and 11th this season. He stopped Santiago Rodriguez from close range just before halftime and made a diving stop in the rain on Maxi Moralez in the 86th minute.