Leaving the Iran nuclear agreement isn't that big of a deal, former Secretary of State Condoleezza Rice said Tuesday.

"The allies love this deal, and I certainly hope that in their meeting with President Trump that [French President Emmanuel] Macron and [German Chancellor Angela] Merkel talk about ways to improve the deal if we're going to stay in it," Rice said on Fox News.

"But if we get out of this deal, it's going to be just fine," she said. "The Iranians, I think, will try and stay in because they do want that investment eventually to start flowing."

Rice added that she would not have signed the Iran deal, and that while there is an argument to be made for staying in it to maintain U.S. alliances, there's no real argument to stay.

[Related: John Bolton: Trump hasn't decided to leave the Iran nuclear deal yet]

"I would probably have stayed in for alliance management purposes, but I have no argument," she said. "If the president decides to pull out of the deal, I have no argument with that."

.@CondoleezzaRice on the Iran deal: “I would not have signed this deal. I don’t think it was a very good deal. I think we were in a hurry to get a deal and we left a lot on the table.” pic.twitter.com/4cJIICp4Ld — Fox News (@FoxNews) May 1, 2018

Trump has until May 12 to decide whether to continue on with the agreement, seek changes, or abandon it. Trump on Monday seemed to indicate once again that he could leave the agreement, and said the U.S. got "nothing" after signing the deal and giving Iran access to billions of dollars.

But Trump also said, "That doesn't mean we won't negotiate a real agreement."

Rice said Israeli Prime Minister Benjamin Netanyahu's dramatic presentation showing that Iran lied about having a nuclear weapons program for her was more proof that it will be hard to trust Iran to tell the truth about whether it's complying with the agreement.

"It says to me that the 2015 nuclear deal, the real issue is verification," she said. "When you know that you have a country that's lied repeatedly, obviously, why trust them now?"

"My concern about the nuclear deal has been the verification regime," she added. "If anything this just makes it even more clear that you can't have a verification regime that gives the Iran regime weeks to clean up the site."

[Opinion: What happens when the US withdraws from the Iran nuclear deal]