"We do face a credibility problem in the eyes of the world when we're talking without acting," Craft said. "There's too many times when the council just repeats conversations [rather] than taking concrete steps forward."
She added that "a credibility gap has implications for public support."
In recent years, there has often been a lack of consensus among the powerful council, with veto-wielding powers Russia, China and the US disagreeing on topics such as Syria, Yemen and Venezuela. Efforts to reform the body have so far proved fruitless.
Craft said the Security Council's Thursday visit to the White House had included a "relaxed lunch with important dialogue with the president."
US President Donald Trump has openly questioned the value of the UN and other multinational organizations.
His pick of Craft, 57, as UN ambassador was seen as controversial by some. She is the wife of a billionaire coal-mining executive and Trump mega-donor with little diplomatic experience.
Craft took up her role at the UN in September, filling a key position that had been left vacant by the Trump administration for eight months.
Craft highlighted her strong focus on human rights during the press conference.
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