The lawsuit was filed just hours after Governor Scott passed the legislation which raises the legal age for buying rifles in Florida and allows the training and arming of school staff, on Friday evening.
The new law also bans the sale or possession of bump fire stocks, gives law enforcement greater power to seize weapons and ammunition from those deemed mentally unfit, and provides additional funding for armed school resource officers, reported CNN.
The NRA suit, filed in the Northern District of Florida, focuses on the part of the law that raises the minimum age to purchase a firearm to 21 from 18.
"This bill punishes law-abiding gun owners for the criminal acts of a deranged individual," executive director of the NRA Institute for Legislative Action Chris W. Cox said.
"Securing our schools and protecting the constitutional rights of Americans are not mutually exclusive."
Seventeen people were killed at the Marjory Stoneman Douglas High School when the 19-year-old former student Nikolas Cruz, opened fire with a semi-automatic military-style rifle.
The lawsuit says the minimum age section of the new law violates the second and 14th amendments of the US Constitution.
The NRA argues people who are 18 years old are considered adults "for almost all purposes and certainly for the purposes of the exercise of fundamental constitutional rights".
The organization also contends federal law already prevents many Americans, 21 or younger, from buying certain types of guns.
Florida Attorney General Pam Bondi, who is named as a defendant, said she was proud of the law.
"This bill is not perfect, and sadly it will not bring back the 17 lives lost in the horrific school shooting, but the safety of our children is not a political issue, it's simply the right thing to do," she said.
A controversial part of the new law is known as the Coach Aaron Feis Guardian Programme, which arms some teachers if both the local school district and local sheriff's department agree.
The $67 million provision is named after the coach who shielded students with his own body and died in last month's shooting.
In response to the signing of the bill, several students told CNN about their excitement.
"We are happy and ready to keep working!!," said junior Connor Dietrich.
"We have much more planned. This is just the beginning," Tyra Hemans said.