Brahimi was in Syria Thursday and Friday to meet with Syrian leaders, including President Bashar Assad, as well as opposition leaders, the BBC reported.
"The crisis is dangerous and getting worse, and it is a threat to the Syrian people, the region and the world," Brahimi, a former Algerian foreign minister, told reporters after his meeting with Assad Friday. "We will make a great effort to make progress, and do our best ... to help the Syrian people."
Brahimi took over as the U.N.-Arab League envoy to Syria from Kofi Annan when Annan's mission expired two weeks ago.
The activist group Syrian Observatory for Human Rights said at least 132 people were killed in Syria Friday, including 18 in Damascus, the capital.
The United Nations said more than 18,000 people, mostly civilians, have died since fighting broke out March 2011.