The gathering is part of the regularly scheduled run-up ministerial meetings ahead of the G7 leaders' June summit in Charlevoix, Que., but its timing is giving foreign ministers a chance to discuss key developments in the North Korea nuclear standoff.
The meeting takes place just days after the group condemned the chemical poisoning of a Russian spy and his daughter in the U.K. Many officials point to Russia as being behind the poisoning, but Moscow has denied involvement in the attack.
"They are I think interested in a unified approach on how we express our profound concern and our disagreement and how we will work together to address them", said the official, who spoke on the condition of anonymity.
The United States said its priorities also included Iran's "malign" regional activities and ending North Korea's nuclear programme. A senior official from one G7 nation said ministers were deeply anxious about what the group saw as a pattern of Russian misbehaviour going back years.
The issue was anticipated to be raised in spiritual discussions between G-7 members, 1 official added.
US President Donald Trump has called the 2015 Iran pact one of the worst agreements ever negotiated and will decide by May 12 whether to restore US economic sanctions on Tehran, which would be a severe blow to the pact.
Trump has threatened to tear the agreement up unless European capitals agree to supplement it with tougher controls on Iran's missile program and future ability to return to nuclear fuel enrichment.
Iranian President Hassan Rouhani said on Saturday Iran's atomic agency was ready with "expected and unexpected" reactions if the United States pulls out of the 2015 deal, which was signed in Vienna.
Also on the agenda is North Korea, which on Saturday said it would immediately suspend nuclear and missile tests and scrap its nuclear test site.
Freeland said she and Mogherini had made a decision to host talks on September 21 and 22 ahead of UNGA just for these "inspiring" female foreign ministers.