“The greatness of the nation of Iran in the region is more than at any other time,” Rouhani said in a speech in Tehran, carried by the state broadcaster.
Rouhani did not directly respond to comments on Sunday by US Secretary of State Rex Tillerson, who called on Iran-backed forces fighting militants in Iraq to “go home.”
But despite its powerful position in the region, Rouhani said Iran’s regime was under threat from fierce infighting between conservatives and moderates at home.
“We should not think that damaging one part of the system will strengthen the other part. No, the whole system will collapse,” he said.
There has been renewed criticism from hard-liners over the nuclear deal Rouhani’s administration signed with world powers.
On Sunday, state television read out in its entirety a letter by Ayatollah Ali Khamenei from 2015 in which he warned against trusting the US and other signatories to the deal.
Although the accord was explicitly endorsed by Khamenei, hard-liners have consistently lambasted Rouhani for going too far in his efforts to rebuild ties with the West.
Those criticisms have become more pointed in recent days as US President Donald Trump has thrown the nuclear deal’s future into doubt, calling for renewed sanctions to rein in Iran’s build-up of influence, particularly in Iraq and Syria.
But Rouhani said his US counterpart was failing in his efforts to undermine the deal.
“Every day (Trump) says this agreement is the worst deal in history. As he put it, it is shameful for America. But still, he hasn’t been able to do anything with this agreement,” Rouhani said.