“We have not received any evidence of intimidation,” Anil K Gayan, the former Mauritius foreign minister heading the AU delegation told journalists.
There have been suggestions some Rwandans may have been coerced into attending ruling Rwandan Patriotic Front (RPF) rallies during the campaign that ended on Saturday night.
Referring to the huge turnout for the RPF, Gayan said: “When you see such large numbers of people at a meeting, you cannot think they have been coerced”, adding: “But crowds do not necessarily translate into votes”.
The AU has 20 observers on the ground to monitor the poll.
The AU chief monitor said he is fully aware of Rwanda’s history and the 1994 genocide.
“This country has been through terrible things so a transition has to take place.”
The Electoral Commission said the campaign had been violence-free.
“There were no incidents. Everything went off very smoothly,” commission spokesperson Pacifique Nduwimana told AFP.
More than five million voters are registered to vote in the election, which begins on Monday at 06:00 (04:00 GMT).
The Commission has accredited 1 394 observers, including 214 from abroad.
Among the other bodies who have sent monitors are the Commonwealth, which counts Rwanda as a new member, and various Western and African embassies.
President Paul Kagame is running against three candidates from parties with links to his RPF and looks assured of re-election.
With additional reporting from AFP