Sen. Marco Rubio (R-Fla.) speaks during Thursday's presidential debate in Charleston, S.C. (TIMOTHY A. CLARY/AFP/Getty Images)

JOHNSTON, Iowa -- Sen. Marco Rubio (R-Fla.) criticized the Obama administration Saturday for reportedly arranging a prisoner swap in exchange for the release of four Americans being held prisoner in Iran.

Campaigning in this suburb of Des Moines, Rubio said he was not aware of the details of the release of Washington Post reporter Jason Rezaian; Saeed Abedini, 35, of Boise, Idaho; Amir Hekmati, 32, of Flint, Mich.; and Nosratollah Khosrawi.

"The fact of the matter is that this tells us everything we need to know about the Iranian regime. That they take people hostage in order to gain concessions. And the fact that they can get away with it with this administration, I think, has created an incentive for more governments to do this around the world," Rubio told reporters.

The Obama administration's decision to swap Cuban prisoners for the release of American contractor Alan Gross and the decision to release Taliban prisoners in exchange for then-Pfc. Bowe Bergdahl means "you are incentivizing people to take Americans hostage and prisoner even if they’ve done nothing wrong."

As for the Iranians held in Iran, Rubio said: "They shouldn’t have been in jail. They should never – I just saw Jason’s [Rezaian] brother on Tuesday night at the State of the Union. He should have never been in jail, he did nothing wrong. This is hostage-taking. It’s pure and simple. Saeed Abedini, the same thing. Governments are taking Americans hostage because they believe they can gain concessions from this government under Barack Obama. It’s created an incentive for more people to do this in the future."

During a rally of more than 300 people here, Rubio was asked how he would deal with Iran as president.

"When I’m president, on the first day in office, I’m going to cancel the Iran deal," he told the crowd to cheers.

Rubio was joined on the trail Saturday by Sen. Cory Gardner (R-Colo.), a member of the Foreign Relations Committee. Gardner also declined to say much about the reported release, saying he hadn't seen the details.

Asked how a prisoner exchange might be perceived by congressional Republicans, Gardner said: "We’d have to know the details. But again, anytime we have a hostage released -- we’ve all clamored for the release of hostages -- I think that is a positive step. However, what is not a positive step or development is the fact that we continue to turn a blind eye to Iran’s ballistic-missile behavior."