"But in exchange for medical technology - and not second-hand equipment."
He has also said that he would accept helicopters in return for the missiles.
Ortega was elected in January, 17 years after the Sandinista National Liberation Front Party (FSLN), the party he led, was voted out of office.
Nicaragua has already destroyed half of the 2,000 missiles supplied by the Soviet Union in the 1980s, when Ortega led the FSLN to oust Anastasio Somoza, then president, in 1979 and fought US-financed Contra rebels throughout the 1980s.
Ortega has warned that a US plan to help neighbouring Honduras to buy aircraft means that Nicaragua should not drop its defences altogether.
Honduras and Nicaragua were rivals during the 1980s, when Washington strengthened Honduras's military and air force and used the country as a base for the Contra rebels it funded to fight Ortega's government.
Honduras says that the light aircraft paid for by Washington are for hunting drug smugglers and helping in natural disasters.