Iran said on Wednesday it will start enriching uranium at a higher level in July and won't give European powers any more time to prevent this move by protecting Tehran from US sanctions.

Iran stopped complying in May with some commitments in the 2015 nuclear deal that was agreed with global powers, a year after the United States unilaterally withdrew from the accord and re-introduced sanctions on Tehran.

Iran said in May it would start enriching uranium at a higher level, unless world powers protected its economy from US sanctions within 60 days. The deadline is July 8.

The spokesperson for Iran's Atomic Energy Organization, Behrouz Kamalvandi, was quoted as saying by Tasnim news agency on Wednesday as saying: "Iran's two-month deadline to remaining signatories of the JCPOA [nuclear deal] cannot be extended, and the second phase will be implemented exactly as planned."

On May 8, in the first phase of pulling out of some nuclear commitments, Iranian President Hassan Rouhani announced a halt to Iran's sales of enriched uranium and heavy water to other countries.

The nuclear deal allows such sales so Iran can keep reducing its stockpiles below maximum thresholds.

Iran said on Monday it would breach curbs on its stock of low-enriched uranium in 10 days.

Britain, France and Germany plan a new push to keep Iran in the 2015 nuclear deal despite Tehran's threat to violate one of its central limits, but they may be nearing the end of the diplomatic road they embarked on more than 15 years ago.

Worries about a military confrontation between Iran and the United States have mounted since attacks last week on two oil tankers near the Gulf. Washington blamed long-time foe Iran for the incidents but Tehran denies responsibility.

Pentagon announced on Monday deployment of about 1,000 more US troops to the Middle East, citing concerns about a threat from Iran.