* U.S. says Iran raises risk of "regional arms race"
* Accuses Iran of providing weapons to Hezbollah, Houthis
* Urges countries to restrict technolgoy transfers to Iran
* Iran rejects U.S. remarks, warns "they may turn violent' (Adds details, background, Iran response)
GENEVA, March 19 (Reuters) - A senior U.S. arms control official said on Tuesday that Iran's missile programme is destabilising the Middle East and raising the risk of a "regional arms race" through the provision of such weapons to armed groups in Lebanon and Yemen.
U.S. President Donald Trump said when he quit a landmark 2015 deal that lifted international sanctions against Iran in exchange for limits on its nuclear activities that it failed to rein in Iran's missile programme or curb its regional meddling.
The United States has accused Iran of defying a U.N. Security Council resolution by carrying out a ballistic missile test and two satellite launches since December.
"Iran's missile program is a key contributor to increased tensions and destabilization in the region, increasing the risk of a regional arms race," Yleem Poblete, Assistant Secretary of State for Arms Control, Verification and Compliance, said in a speech to the U.N.-sponsored Conference on Disarmament.
"Iran must immediately cease activities related to ballistic missiles designed to be capable of delivering nuclear weapons, and halt the proliferation of missiles and missile technology to terror groups and other non-state actors," she said, denouncing Iran's support to the Houthi movement in Yemen and to Hezbollah in Lebanon.
She said Iran had provided ballistic missiles to the Houthis that were fired into Saudi Arabia and unmanned aerial systems to Houthi groups that enable strikes against land-based targets in Saudi Arabia and the United Arab Emirates.
"We are committed to aggressively countering Iran's regional proliferation of ballistic missiles and its unlawful arms transfers," she added.
Poblete urged "all responsible countries" to enforce United Nations Security Council resolutions restricting the transfer of missile-related technologies to Iran.
She further accused Iran of "pursuing pharmaceutical-based agents for offensive purposes", but did not elaborate.
An Iranian diplomat took the floor to reject her remarks as "cheap, unprofessional, false, irrelevant and pathetic" and accused the United States of "sabotaging" the Geneva forum.
"We should all be truly worried about the U.S. representative's misbehaviour as we all warn that they may turn violent since they lack any human logic to talk and listen in a normal manner as we are used to," he said.
(Reporting by Stephanie Nebehay, Babak Dehghanpisheh and Tom Miles; writing by Stephanie Nebehay; editing by William Maclean)
Our Standards: The Thomson Reuters Trust Principles.