Secretary of State Rex Tillerson and AU commission chairman Moussa Faki Mahamat discussed security and counter-terrorism, trade and development, corruption and conflict in an hour-long meeting at the continental body's headquarters in the Ethiopian capital.
Looming over the meeting was Trump's alleged description of Africa as a "shithole" in January, which forced the president to pen a letter reaffirming his commitment to the continent and dispatch his top diplomat to try to heal rifts.
The slur was in the past, Faki said.
"I received a letter written by President Trump to myself and I shared that with other African leaders. I believe this incident is in the past," he said.
Tillerson's five-nation Africa tour - to include Djibouti, Kenya, Chad and Nigeria - has been described by analysts as a "listening tour."
Chad, Kenya and Nigeria are all battling Islamic extremism, with help from the US, while Djibouti hosts the only permanent US military base on the continent. "The purpose of my trip is to listen to what the priorities of the countries here on the continent are and see where there is good alignment," said Tillerson.
Tillerson praised the AU as a "force for good."
He and Faki discussed continued US support for African counter-terrorism forces in Somalia and the Sahel but no concrete commitments were given.
Tillerson said the AU Mission in Somalia is "clearly an example of countries coming together to counter terrorism, promote stability and enable the delivery of much-needed aid."
Tillerson's trip to Ethiopia is scheduled to briefly overlap with a visit by Russian Foreign Minister Sergei Lavrov, who said he had requested a meeting. Washington denied receiving an invitation to talks.
"We sent proposals to the Americans and they said they will think about that but later. As you know, they announced that there will be no meeting and that no discussions [about it] have taken place at all," Lavrov said in Zimbabwe.