The Islamic republic said on Monday it fired the rocket to mark the opening of its first space centre, which is expected this year to put an Iranian-built satellite into space for the first time.
The White House, already at loggerheads with Iran over its nuclear drive, described the firing as an "unfortunate" move that risked isolating Tehran further from the world.
"Scientific achievements should not make anyone worried," retorted Iranian government spokesman Gholam Hossein Elham.
"Those who are worried are thinking from a point of view of making threats and pressure. They are guilty of discrimination in science when they themselves are equipped with destructive and illegal weapons," he told reporters.
Although Iran did not give details on the height reached by the rocket or its technical specifications, the launch was hailed by the local press as a major step forward for Iranian science.
"The Islamic republic – the eleventh country in space," trumpeted the headline of the conservative daily Jomhouri Islami.
"Iran's first ambassador in space," crowed the ultra-hardline Kayhan daily.
US State Department spokesman Sean McCormack described the rocket launch as "another troubling development", saying Iran could use the same technology for launching satellites to fire ballistic missiles.
The rocket launch was believed to be the second time Iran has attempted to put an object into space after it claimed the successful firing of a missile above the atmosphere in February 2007.
The United States has been leading international efforts to pressure Iran to freeze controversial nuclear activities, which the West fears could be used to make a nuclear weapon.