Maduro was speaking at an outdoor military event in Caracas, Venezuela's capital, to mark the 81st anniversary of the Venezuelan army.
The explosions occurred near a stand where the president was speaking, officials said.
The injured soldiers were participating in a military-style parade honoring the National Guard, said Jorge Rodriguez, the information minister.
"All of the work we have done immediately after has allowed us to establish with evidence that it was an assassination attempt," Rodriguez said in a news conference. "Whoever carried out this attack, failed."
Maduro, who won a second six-year term in May, was sworn into office April 2013 after Hugo Chavez died of cancer.
The president was expected to address the nation on the event after meeting with his ministers and military commanders.