A statement on the npower League One outfit's website confirmed the duo were recalled "due to injury and suspensions".
It continued: "With David Gray and Darius Charles suspended, Marcus Haber's international call up as well a long list of injuries, Gary Smith has opted to bring both back to the Lamex."
N'Gala made six appearances for the Bees after arriving in February while Lopez played five times and netted a hat-trick in the 4-1 thrashing of Morecambe.
Edgar Davids has responded to the loss of Lopez by recalling striker Harry Crawford from his loan spell at Dartford.
The 21-year-old, who joined Barnet from the Darts in January, had returned to his former club for regular football after failing to force his way into the Bees' starting line-up.