Iranian Foreign Minister Abbas Araghchi said on Tuesday that there was no ceasefire agreement with Israel as of now, but if it stopped its attacks then Tehran would also stop firing.
"As of now, there is NO 'agreement' on any ceasefire or cessation of military operations," Araghchi posted on social media, shortly after the US president announced a deal would begin around 0400 GMT.
Araghchi added that if "the Israeli regime stops its illegal aggression against the Iranian people no later than 4 am Tehran time, we have no intention to continue our response afterwards."
US President Donald Trump announced that Iran and Israel had agreed to a staggered ceasefire beginning at approximately 0400 GMT Tuesday that would bring about an 'official end' to the 12-day conflict.
"It has been fully agreed by and between Israel and Iran that there will be a Complete and Total CEASEFIRE," Trump wrote Monday on his Truth Social platform.
The announcement comes after Qatar intercepted an Iranian missile attack on the major US military base on its soil.
Bright flashes lit up the night sky and blasts echoed across wealthy Doha in an attack that followed US strikes on Iranian nuclear sites over the weekend.
The missiles targeted Al Udeid Air Base, the biggest US military facility in the Middle East, in what Qatar's foreign ministry condemned as a "flagrant violation" of its sovereignty.