DUBAI (Reuters) - Iran is determined to boost its defense capabilities despite mounting pressure from the United States and its allies to curb its ballistic missile program, Supreme Leader Ayatollah Ali Khamenei said on Thursday.

Supreme Leader Ayatollah Ali Khamenei waves his hand, as he delivers a speech on the first day of Persian New Year, also known as Nowruz in Mashhad, northeast of Tehran, Iran March 21, 2019. Khamenei.ir/Handout via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. NO RESALES. NO ARCHIVES.

“We need to take Iran to a point that enemy understand that they cannot threaten Iran ... America’s sanctions will make Iran self-sufficient,” Khamenei said in a speech broadcast live on state TV.

President Donald Trump withdrew the United States last May from a 2015 nuclear deal between Iran and six major powers, saying it gave too much away to Iran, and reimposed far-reaching U.S. sanctions.

The U.S. sanctions aim to force Iran to accept tougher restrictions on its nuclear work, drop its ballistic missile program and scale back support for militant proxies in Middle East conflicts from Yemen to Syria.

Iran says its missile program is purely defensive and has rejected the curbs on it demanded by the United States. Tehran says it has missiles with a range of up to 2,000 km (1,250 miles), which puts Israel and U.S. military bases in the region within reach.

The other signatories to the nuclear deal - Germany, France, Britain, the European Union, Russia and China - have remained committed to the agreement and have been trying to salvage the pact by a mechanism to circumvent Trump’s sanctions.

Khamenei, a hardliner who has the ultimate say on all major foreign and domestic policy in the Islamic Republic, said the European signatories of the deal had failed to maintain Iran’s economic interests.

“They have always stabbed Iran in the back ... The Western countries have proved they cannot be trusted,” he said in the speech in the holy Shi’ite city of Mashhad.

Iranian leaders have threatened to exit the nuclear deal unless the European powers enable Tehran to receive economic benefits.

“This mechanism set by the Europeans is like a bitter joke,” Khamenei said, referring to a channel opened by the European signatories of the deal for non-dollar trade with Iran to get around the U.S. sanction.