Iran's Supreme Leader Ayatollah Ali Khamenei has slammed "arrogant" powers for striving to bring the country "to its knees".
A twitter account, believed to be operated by the Ayatollah's office, also claimed that the US is using Isis to keep war among Muslims alive.
Tweeting about the 12-year dispute over Iran's nuclear goals with six world powers, Ayatollah Ali Khamenei said: "In the nuclear issue, arrogants [sic] have made their best to bring Iran to its knees but they were not able and will not be able to do so."
He then added several other tweets claiming that the US-led coalition against the Islamic State (Isis) is a "blatant lie".
The Twitter account does not have a blue verification symbol, which is a stamp of approval from the network over the identity of the user. Iran experts have said that they believe the @khamenei_ir account is run by the office of Ayatollah Ali Khamenei.
On 9 November, Ayatollah Ali Khamenei used Twitter to state that Israel should be wiped off the global map.
He set out "the only means of bringing Israeli crimes to an end", adding that "during its 66 years of life so far, the fake Zionist regime has tried to realise its goals by means of infanticide, homicide, violence and iron fist."