The White House has quoted US President Donald Trump as saying he will decide within two weeks whether to take military action on Iran, while leaving the door open to negotiations.

Trump has hinted at the possibility of US military intervention in the ongoing conflict between Israel and Iran, saying, "I may do it, I may not do it."

At a news conference on Thursday, White House Press Secretary Karoline Leavitt acknowledged the considerable speculation about the issue.

She read out a message from Trump. It said, "Based on the fact that there's a substantial chance of negotiations that may or may not take place with Iran in the near future, I will make my decision whether or not to go within the next two weeks."

In response to a reporter's question, Leavitt confirmed that correspondence between the Trump administration and the Iranian government is ongoing.

She added, "If there's a chance for diplomacy, the president is always going to grab it, but he's not afraid to use strength as well."

She declined to give details, including how the two sides are communicating.

The White House says Trump plans to hold daily National Security Council meetings through the weekend as he weighs future responses to the Iranian situation.