Washington, Apr 21 (IANS): Despite his administration's certification of Iran's compliance with the 2015 nuclear deal, US President Donald Trump on Thursday accused Iran of "not living up to the spirit" of the nuclear deal.

"They (Iranians) are doing a tremendous disservice to an agreement that was signed. It was a terrible agreement. It shouldn't have been signed," Xinhua news agency quoted Trump as saying.

When asked by a reporter whether the White House had any reasons to suspect that Iran was cheating on the nuclear deal, Trump appeared to ignore the question, answering only that his administration was analyzing the 2015 nuclear deal.

"We'll have something to say about it in the not-too-distant future," said Trump. He did not elaborate.

In a letter to House Speaker Paul Ryan on Tuesday, US Secretary of State Rex Tillerson certified that Iran was compliant through Tuesday with its commitments under the 2015 Iran nuclear deal.

It was the first certification of Iran's compliance issued by the Trump administration. Like his predecessor former U.S. Secretary of State John Kerry, Tillerson is required to send the certification every 90 days.

However, calling Iran "a leading state sponsor of terror," Tillerson informed the Congress that the Trump administration had directed a full review of the 2015 nuclear deal to evaluate whether continued sanctions relief was in the US national security interests.

During his campaign, Trump repeatedly criticized the Iran nuclear deal, calling it "the worst deal ever negotiated." He also suggested that he would force Iran to return to the negotiation table or risk the accord being dismantled.

Iran and six world major countries -- the United States, Britain, China, Russia, France and Germany -- reached an agreement on the Iranian nuclear issue in July, 2015 that puts Iran on the path of sanctions relief but more strict limits on its nuclear program.

The deal sets limits on Iran's nuclear activities as it will take Tehran at least one year to produce enough fissile materials for producing a nuclear weapon, and allows regular inspections of the facilities inside Iran.

In return, the United States and the European Union will suspend nuclear-related sanctions against Tehran, with the lifting of all past UN Security Council sanction resolutions.