President-elect Joe Biden, who defeated Trump at the ballot box in November, has signaled a willingness to return to diplomacy with Iran after four tense years under the outgoing president.
"Some say you are overexcited by the advent of Mr. Biden. No, we are not, but we are very happy to see Trump leave," he said in televised comments at a cabinet meeting, AFP reported.
"Thank God, these are his final days," Rouhani added, calling Trump a "tyrant", "the most unruly, lawless president" and a "terrorist and murderer."
The Electoral College confirmed Biden as the next US president on Monday even as the incumbent continues to refuse to accept defeat.
The formal handover of power will take place on January 20 when Biden is sworn in.
In 2018, Trump pulled the US out of the 2015 Iran nuclear deal, officially called the Comprehensive Plan of Action (JCPOA), and reimposed unilateral sanctions.
The JCPOA was signed between the Islamic Republic and the P5+1 group of countries, the US, the UK, France, Russia, and China plus Germany, and ratified in UNSC Resolution 2231.
Trump "creates obstacles for us purchasing (COVID-19) vaccines, (that is) how much this person is bereft of all ethical and human principles," Rouhani said.
Iran is the country hardest-hit by the coronavirus pandemic in the Middle East with nearly 53,000 deaths from more than 1.1 million cases, according to official figures.
Vaccines and other humanitarian goods are supposed to be exempt from US sanctions but in practice few if any banks are willing to risk processing Iranian transactions for fear of incurring heavy penalties in the US courts.
Rouhani said the outcome of the US election showed the American people's desire for a "law-abiding" president and called on the Biden administration to live up to the expectation.
"If it wants to be on the correct path, it's there, and if it wants the wrong one, it's also there," he said.
Rouhani also stressed that today’s situation is completely different from 2015, when long-running negotiations culminated in the JCPOA.
“In 2015, when we were negotiating the JCPOA, the sword of six resolutions was above our head, but today this sword is broken. Back then, the PMD (possible military dimensions in the nuclear case) was another threat that does not exist today,” Rouhani said, according to Press TV.
“In 2015, the world public opinion was formed in such a way that if Iran makes a commitment, it will not fulfill it. However, we have proved in the JCPOA that we are the most committed country in the world. We negotiate hard and obsessively, but if we sign [a deal], we will honor our promise. This is while even the P4 + 1 countries failed to implement their obligations.”
He highlighted the US isolation at the UN given its failure to garner support for Iran anti-Iran resolutions.
“In those days [prior to the deal], the P5+1 group was against us, but today the United States is alone and all the world countries, except for one or two small mercenary states affiliated to America, oppose the US’s withdrawal from the JCPOA,” Rouhani emphasized.
The world has learned about the resistance of the Iranian nation, he said, noting, “We are standing on our own feet, but at the same time, if [the opposite side] returns to its commitments, we will also return to all our commitments.”