TEHRAN, Iran -- Within an hour of President Trump's announcement that he would not certify Iran's compliance with the nuclear deal, Iran's president took to the air, pushing back hard.

President Hassan Rouhani called Mr. Trump's accusations "abusive" and "downright wrong."

Reza Abdolnaleki CBS News

Certainly people watching in the country's capital were stunned by Mr. Trump's claim that, back in 2015, the regime was on the verge of collapse.

"He's really crazy," said shopkeeper Reza Abdolmaleki. "Really crazy."

Mr. Trump, Rouhani said, doesn't understand that the U.S. can't change a multinational agreement all by itself. So for that reason, Iran will stay in the nuclear deal.

Iranian Pres. Hassan Rouhani on Friday

However, he hinted Iran may escalate its conventional weapons program, possibly its development of ballistic missiles.

For millions of Iranians -- especially the young who counted on improved relations with the U.S. and the rest of the world to bring investment, jobs and reform -- this is a black day.

They feel hard-liners will now gain ground, arguing the U.S. can't be trusted.

President Trump speaks about Iran and the Iran nuclear deal REUTERS

The only two powers in the region who were cheering are Iran's arch enemies: Saudi Arabia and Israel.

"If this Iran deal is left unchanged, one thing is absolutely certain: In a few years' time, the world's foremost terrorist regime will have an arsenal of nuclear weapons," said Israeli Prime Minister Benjamin Netanyahu.

Iranian Foreign Minister Jawad Zarif also joined the war of words Friday, tweeting: