The neighbor saw a man attempt to coax the girl into his van Monday afternoon at a playground, KRQE-TV, Albuquerque, reported.
"The child was being resistant to his enticement and that is what caused him to get out of the car and actually push her into the van," Albuquerque police Officer Robert Gibbs said.
The neighbor, whose name was not reported, got in his car and tailed the van while calling 911.
Police say the suspected kidnapper, Phil Garcia, noticed he was being followed and tried to get away -- but ended up crashing the van and fleeing without the girl on foot.
Garcia was apprehended by police on the mesa. The girl is OK but her mother was very distressed, police said.
The neighbor told police he just acted on instinct. Gibbs said the neighbor's action may have saved the girl's life.
"(Garcia) probably would not have attempted or tired to get away in the desert probably would have tried to go down a normal road taken her somewhere probably sexually assaulted her and could have hurt or actually killed her," Gibbs said.
Garcia, who has no criminal record involving sex crimes, has had two DWI convictions, the report said.