Iran said Thursday that the U.S.'s reported plan to impose new sanctions against its ballistic missile program would be arbitrary and illegal.

"As we have declared to the American government ... Iran's missile program has no connection to the (nuclear) agreement," Iranian state television quoted Foreign Ministry spokesman Hossein Jaber Ansari as saying, according to Reuters.

The Wall Street Journal reported Wednesday that the U.S. Treasury Department is preparing to issue fresh sanctions against at least 12 companies and individuals in Iran, Hong Kong and the United Arab Emirates for their alleged role in developing Tehran's ballistic missile program.

"Iran will resolutely respond to any interfering action by America against its defensive programs," Ansari said, denouncing the new sanctions as "arbitrary and illegal," according to Telesurtv.

If the sanctions are imposed, they would be the first by the U.S. since Iran entered a nuclear deal with the P5+1 world powers in July. Under the deal, Washington plans to drop separate economic sanctions as early as next month in exchange for Iran halting key aspects of its nuclear program to prevent it from developing a nuclear weapon.

The prospect of new sanctions comes after Iran tested a medium-range Emad rocket in October. The United Nations say that the rocket was capable of carrying a nuclear warhead - which Iran denies - and was a violation of a U.N. Security Council resolution.

Such ballistic missile tests are banned under the Security Council resolution 1929 approved in 2010. The resolution will be invalidated once the new nuclear deal goes into effect, however under a new Security Council resolution adopted after the nuclear deal, Iran will still be "called upon" to not conduct work on ballistic missiles designed to deliver nuclear weapons, for up to eight years, according to The Guardian.

Iran says that because the resolution only bans missiles "designed" to deliver nuclear weapons, not missiles that are "capable of" carrying warheads, the resolution would not affect its military program, because Tehran does not pursue nuclear weapons.