"Progress" is being made to keep the United States in the Iran nuclear deal, British Ambassador to the U.S. Kim Darroch told CBS's "Face the Nation" on Sunday.

"We have been talking at senior official level to the administration with our French and German colleagues for several weeks now," Darroch said. "We think we're making progress. We haven't got there yet. We have a few days left to see if we can find a way through."

President Donald Trump set a May 12 deadline for his decision on whether or not he will pull out of the Iran agreement in which Tehran agreed to curb its nuclear program in return for sanctions relief.

"We think it's a good deal," Darroch said. "It's not a perfect deal, no deal ever is perfect, and the president is rightly concerned about Iran's regional activities, which are malign and damaging to security and stability. And he doesn't like the fact that missiles aren't covered.

"He's not happy about the sunset clauses, he thinks the inspections regime should be tougher. On those issues, we have ideas we think that we can – we can find some language, produce some action that meets the president's concerns."

The British ambassador said that efforts are geared towards keeping the U.S. in the agreement, but should the Trump administration choose to withdraw, "My government has said that as long as Iran is in compliance with the deal and wants to stick with it, that will be our position as well."

Darroch also said that Trump and British Prime Minister Theresa May spoke Saturday about the Iran deal and that the president said "a final decision hasn't yet been taken."

The interview came just days before British Foreign Secretary Boris Johnson's visit to Washington for two days of talks in an attempt to salvage the accord, The Washington Post reported.

Last month, French President Emmanuel Macron also visited the U.S. to make his case to Trump to remain in the deal.