"I think you'll see them continue to test these missiles with longer and longer range and accuracy," Rubio said on "The Story with Martha MacCallum." "They sponsor terrorism all over the region, primarily as proxy forces that by the way killed and maimed hundreds of Americans in Iraq. They were the authors and the builders of those I.E.D's that hurt our troops there in the past. And you've seen the recent attacks as well and things they've done in the region.
"This is par for the course with a terroristic regime that needs to be reined in."
Iran announced last week that it had exceeded the amount of low-enriched uranium allowed under the 2015 nuclear deal. On Monday, it was revealed Iran had begun enriching uranium at 4.5 percent purity, well past the 3.67 percent purity allowed under the agreement.
Experts warn that higher enrichment purity and a growing stockpile will narrow the one-year window Iran would need to have the necessary material for an atomic weapon, something that Tehran denies it wants.
Critics continue to blast President Trump for pulling out of the Iran deal last year, including former Secretary of State Hillary Clinton, the president's 2016 election opponent.
On Tuesday, Rubio called the Iran deal "ridiculous" and defended Trump's decision to withdraw from the agreement.
"The only thing it said is that you couldn't enrich uranium and reprocess plutonium but you can continue to do the missiles, you can continue to do the cyber attacks. You can continue to sponsor the terrorism. That's ridiculous," Rubio said, later adding, "The president was right to get us out of the deal."
The Florida senator also promised a "strong and definitive" response if Iran attacks American interests.
"If Iran attacks the United States, they're gonna get a response that will be strong and definitive," Rubio said. "That said, the sanctions continue in place... We are not going to put back [sanctions] relief so that they can have millions and millions of more dollars every month that they can use to build the rockets, [and] to sponsor the terrorism."