The AU on Wednesday called it a flagrant violation of ceasefire agreements signed by the group.
It said the 17 were detained on 10 May and later released the same evening, but the force was unable to return to their base until the following day so as not to travel at night.
"The forceful detention of any AU personnel while performing their lawful duties is unacceptable and a flagrant violation of the commitments undertaken by the parties," the AU statement said.
The rebel Sudan Liberation Army (SLA) said it had detained the 17 in South Darfur because a representative of the group was not with the AU patrol and the AU had not notified the rebels.
The AU said it did not need to notify any party that they were entering their areas.
Earlier, representatives of Darfur's local administration signed an agreement in Libya with two main Sudanese rebel groups to adhere to a ceasefire.
The talks on Wednesday between Darfur's local administration, the Sudan Liberation Movement and the Justice and Equality Movement also agreed on facilitating the passage of international aid convoys and trade in the area.
Libyan leader al-Gaddafi is trying
to broker a Darfur peace deal
The declaration was read out and signed in the presence of Libyan President Muammar al-Gaddafi during his meeting with the participants in Tripoli.
The parties discussed security, human and social situations in Darfur and ways and means to ensure peaceful coexistence.
Head of the civil leadership in Darfur, Salah Muhammad al-Fadhl, told Aljazeera's correspondent in Libya that "the agreement is aimed at reaching a full and permanent peace in Darfur".
"We have urged all parties, particularly armed groups, and our brethrens at the government to speed up holding talks to settle pending political issues," he added.
Wednesday's declaration comes just five days before Libya hosts a five-party summit to discuss developments in Darfur.
Al-Gaddafi announced on Wednesday that the summit would be held in Tripoli on Monday.
Attending the summit, which was originally scheduled to take place on Sunday and Monday in the Egyptian resort of Sharm al-Shaikh, will be the heads of state of Sudan, Egypt, Libya, Nigeria and Chad.
Fighting has pitted Arab militias
against African tribal groups
The announcement comes after al-Gaddafi, who has sought to mediate in the Darfur conflict, received a pledge from tribal leaders in the region that they would work towards reconciliation.
No reason was given for the change in timing and location of the summit, which had already been postponed from late April when it was to be held alongside the New Partnership for Africa's Development summit in Sharm el-Sheikh.
Continued fighting between allegedly government-backed Arab militias and African rebel groups in Darfur has displaced close to two million people and killed more than 180,000 since 2003.
Meanwhile, Sudan's President Omar al-Bashir, speaking to Aljazeera's correspondent in Khartoum, has confirmed his government's determination not to hand any Sudanese over to the International Criminal Court.
Al-Bashir said he was ready to confront the US and the international community in this respect - "even they came close to the gates of Khartoum", as he put it.
On the question of opposition Popular Congress Party chief Hasan al-Turabi's fate, he said he had not taken a decision to free him.
But he indicated that such a step might be taken before 9 July.