US President Donald Trump said Monday it was "time for change" in Iran and that the country's people were "hungry" for freedom, after days of deadly protests against the government in Tehran.

"Iran is failing at every level despite the terrible deal made with them by the Obama Administration," Trump tweeted, referring to the nuclear pact sealed under his Democratic predecessor Barack Obama.

"The great Iranian people have been repressed for many years. They are hungry for food & for freedom. Along with human rights, the wealth of Iran is being looted. TIME FOR CHANGE!"