The Strait of Hormuz is an "invincible red line" and Iran will not allow any US interference in the waterway, Iran's military has warned, Sky News reports.
The US restarted strikes on Iran last week in response to what it said were attacks on commercial shipping in the strait.
It also reimposed a naval blockade on Iranian ports around the strait, while Donald Trump also announced his intention on charging tolls in the strait before rowing back on the idea.
A spokesperson for Iran's top military command, quoted by the Fars state news agency, said: "Under no circumstances and in no way will we allow America, as a foreign and extra-regional country, to interfere in the Strait of Hormuz.
"This is Iran's invincible red line."