US President Donald Trump has reacted to the closure of the Strait of Hormuz by saying "Iran can't blackmail us".
He says that American talks with Iran are going well and that he expects to have more information over the weekend, the Associated Press reports.
Trump declined to take reporters' questions about Iran but said, "We have very good conversations going on."
LIVE UPDATES: Iran fires on ships in Strait of Hormuz
He says Iran "got a little cute," later adding, "They wanted to close up the strait again," referring to the Strait of Hormuz.
"They can't blackmail us," Trump said.
The US president was speaking shortly after Iran's Islamic Revolutionary Guard Corps (IRGC) has announced it will blockade the Strait of Hormuz, the organisation's naval forces said in a statement on Telegram overnight.
"Approaching the Strait of Hormuz will be considered cooperation with the enemy, and any offending vessel will be targeted," the IRGC statement read.
After declaring the waterway open on Friday, Iran reimposed restrictions on the passage of ships on Saturday, citing "repeated breaches of trust" by the US in the two sides' ceasefire.
READ MORE: US Navy denies food shortages after grim photos emerge from blockade ships
The British military says two gunboats from Iran's Revolutionary Guard opened fire on a tanker transiting the Strait of Hormuz after Iran said it had reimposed restrictions on the vital waterway.
Hours later a container ship was hit by "unknown projectile which caused damage to some of the containers" about 46 kilometres off the coast of Oman, the UKMTO said.
– Reported with CNN, Associated Press
NEVER MISS A STORY: Get your breaking news and exclusive stories first by following us across all platforms.
- Download the 9NEWS App here via Apple and Google Play
- Make 9News your preferred source on Google by ticking this box here
- Sign up to our breaking newsletter here
