"They give the slogan of change but in practice no change is seen ... We haven't seen any change," Supreme Leader Ayatollah Ali Khamenei said in a televised speech in the northeastern city of Mashhad.
He stressed that a change of US "words" was not enough and added: "We will watch and we will judge (the new US administration) ... You change, our behavior will change."
In a message timed for the Iranian celebration of Nowruz, a holiday marking the arrival of spring, Obama said Friday he wanted to pursue "constructive ties" with Tehran and engage in broad diplomacy.
That same day, Khamenei made no mention of Obama's video message but vowed that world powers could not stop Tehran's nuclear program, which the Islamic Republic insists is for the peaceful generation of electricity.
Aliakbar Javanfekr, an aide to Iranian President Mahmoud Ahmadinejad, said on Friday that Iran welcomed "the interest of the American government to settle differences" but that Washington "should realize its previous mistakes and make an effort to amend them."