Speaking at a press conference on Friday, she said, "We're obviously at a pivotal point."
She made the remarks after US Secretary of State John Kerry said on Thursday the P-5+1 group of countries will continue to move ahead toward a final nuclear deal with Iran with maximum care.
Kerry told a forum hosted by The Atlantic magazine that any approach toward an agreement with Iran over its nuclear energy program "will be based on expert advice".
He added any decision with regard to a deal with Iran must be based on fact and science. "This must not become an ideological, or a political decision."
Kerry further said that the coming three weeks will be crucial for reaching a compromise.
Iran and the P5+1 group — Russia, China, France, Britain, the US and Germany — are negotiating to narrow their differences over the Islamic Republic's nuclear energy program ahead of the deadline.
Sources close to the Iranian negotiating team say the main stumbling block to resolving Western disputes over Iran's nuclear issue is the removal of sanctions, not the number of centrifuges or the level of uranium enrichment.
A senior Iranian official has described the time remaining for concluding a final deal as the best opportunity for the P5+1 group to resolve its differences with Iran.
"The pressure of sanctions and excessive demands cannot solve the problem in [the ongoing] negotiations. They (world powers) have experienced [the attitude of] the Iranian nation, which stands by its values at whatever cost. Therefore, [the remaining time] is the best opportunity for them to resolve their issues with Iran," the head of Iran's Strategic Council on Foreign Relations, Kamal Kharrazi, said in a report published on Thursday.
Kharrazi, who served as Iran's foreign minister from 1997 to 2005, said the possibility of conclusion of a final accord hinges on the decision of the opposite side — six world powers.