Over the weekend, US Secretary of State Mike Pompeo charged that Iran tested a medium-range missile capable of carrying multiple warheads and striking parts of Europe and the entire Middle East.

He said the test violated UN Security Council Resolution 2231, which endorsed the Iran nuclear deal signed by world powers with the Islamic republic.

"The Iranian government claims that its missile testing is purely defensive in nature. It's not defensive," Washington's Iran special envoy Brian Hook told reporters aboard Pompeo's plane as he traveled to Brussels for a NATO meeting.

"We would like to see the European Union move sanctions that target Iran's missile program."

Hook said President Donald Trump's campaign of "maximum pressure" on Tehran since withdrawing from the Iran nuclear deal "can be effective if more nations can join us in those (sanctions)."

"It is a grave and escalating threat, and nations around the world, not just Europe, need to do everything they can to be targeting Iran's missile program," he added.

Hook said "progress" was being made on getting NATO allies to consider a proposal to target individuals and entities that play key roles in Iran's missile program.

The United States decided in May to withdraw from the 2015 nuclear deal and reimpose sanctions on Iran.

EU countries have denounced the move and are working to preserve the nuclear deal, even though they have also criticized Iranian positions on other matters.