US President Donald Trump speaks to reporters before departing from the White House in Washington D.C., the United States, June 22, 2019. Donald Trump on Saturday said that the United States would impose major additional sanctions against Iran on Monday. (Xinhua/Ting Shen)

President Donald Trump said on Saturday that the United States would impose major additional sanctions against Iran on Monday.

"We are putting major additional Sanctions on Iran on Monday," Trump tweeted on Saturday, without providing any other details.

"Iran cannot have Nuclear Weapons!" he stressed in the same tweet.

Before leaving for Camp David earlier in the day, Trump told reporters that additional sanctions would be moving forward against Iran, with some being implemented "slowly" and some "more rapidly."

Asked if military action is still on the table, he said that "it's always on the table until we get this solved."

In response, Iran military warned the United States against the mistake of taking military actions on Iran, saying any attack would draw Tehran's "crushing response and cost the US dearly," Tasnim News Agency reported on Saturday.

Trump on Friday confirmed that he authorized the military strikes against Iran in retaliation for downing a US military drone but called off the operations 10 minutes before they were to be implemented.

Trump noted that the potential casualties of the impending strikes, which might be 150 people, are "not proportionate" to the loss of a US unmanned aircraft.

The US military confirmed on Thursday that an RQ-4 Global Hawk Unmanned Aircraft System (UAS) was shot down by an Iranian surface-to-air missile system at approximately 2335 GMT on Wednesday. Iran, however, claimed the drone downed in the southern part of the country had crossed Iranian borders.

This incident further inflamed the ongoing tensions between Washington and Tehran, which have been on the rise since the attack on two oil tankers last week in Gulf of Oman as well as Iran's threats of not complying with the 2015 Iran nuclear deal.