President Donald Trump on Tuesday told Iranians to keep protesting and said help was on the way, but did not elaborate on whether that meant possible U.S. action.
"Iranian Patriots, KEEP PROTESTING - TAKE OVER YOUR INSTITUTIONS!!!... HELP IS ON ITS WAY," Trump said in a post on Truth Social.
He said he had canceled all meetings with Iranian officials until the "senseless killing" of protesters stopped.
Trump has previously said military action is among options he is weighing to punish Iran, which is seeing its biggest anti-government protests in years. About 2,000 people including security personnel have been killed in protests in Iran, an Iranian official said on Tuesday.
Late on Monday Trump also announced 25% import tariffs on products from any country doing business with Iran - a major oil exporter.
Iran's Foreign Minister Abbas Araqchi told Al Jazeera on Monday that he had continued to communicate with U.S. special envoy Steve Witkoff during the protests and Tehran was studying ideas proposed by Washington.