Iran has said it has "no intention of increasing the range" of its missiles, amid threats of European as well as US sanctions over its ballistic programme.
Iran has voluntarily limited the range of its missiles to 2,000km, sufficient to reach Israel and Western bases in the Middle East.
But the United States and its allies have accused Iran of pursuing enhanced missile capabilities that also threaten Europe.
"Iran has no technological or operational constraints to increasing the range of its military missiles," the secretary of the Supreme National Security Council, Admiral Ali Shamkhani, said.
"But while constantly striving to improve accuracy, solely based on its defence doctrine, (it) has no intention of increasing the range of (its) missiles," the official IRNA news agency quoted him as saying.
US President Donald Trump cited Iran's missile programme as one of the reasons why he pulled the US out of a landmark 2015 nuclear deal between Iran and major powers last year.
European governments have stuck by the nuclear deal but some have demanded a supplementary agreement to tackle Iran's ballistic missile programme and its interventions in regional conflicts.
Admiral Shamkhani's comments come after France warned on Friday that it was ready to impose new sanctions if talks on a supplementary deal fail to make progress.
"We have begun a difficult dialogue with Iran... and, unless progress is made, we are ready to apply sanctions, firmly, and they know it," Foreign Minister Jean-Yves Le Drian said.
Iran retorted that French arms sales in the Middle East were one of the real sources of instability in the region.
Iran's space programme has also come under Western criticism, with Washington charging that an abortive satellite launch earlier this month was cover for a bid for an intercontinental ballistic missile capability.
But Admiral Shamkhani, who was addressing the national conference on space technology in Tehran, said Iran could accept no limitations on its satellite launches.
"We will vigorously carry on with the development of our space programme," IRNA quoted him as saying.
Iran tried unsuccessfully to put a satellite into orbit on January 15, and plans to make a second attempt soon.
US Secretary of State Mike Pompeo accused Iran of violating UN Security Resolution 2231 of 2015.
It calls on Iran "not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons".
Iran has always denied seeking any nuclear weapons capability but has said repeatedly that it needs its missile programme as a matter of national security.
In the 1980-1988 war launched by Saddam Hussein's Iraq, Iranian cities were devastated by Iraqi missiles in a bombing campaign dubbed the "war of the cities".
Iranian officials say that Western sanctions have starved its air force of spare parts and replacement aircraft, severely limiting its operational capacity and forcing Iran to rely on its missile programme.
The council run by Admiral Shamkhani is in charge of drawing up Iranian military and security policy.
A former defence minister and adviser to supreme leader Ayatollah Ali Khamenei, he was appointed as its secretary by President Hassan Rouhani in 2013.