Williams, who converted to Islam in 2009, was given the week off by his Super Rugby team to work with the Muslim community as it deals with the last Friday's shooting, which killed 50 people at two mosques in Christchurch.
"I think we have to be gentle at the start because there are a lot of mixed emotions," Williams told TVNZ before the televised call to prayer and service at Hagley Park, close to the Al Noor mosque where a majority of victims were killed.
"You have just got to do what is best for the victims, but then moving forward I think something beautiful is going to happen."
The two-times World Cup winner, the first Muslim to play for the All Blacks, was visibly shaken by the shooting and posted a tearful message of support on his social media accounts, shortly after news of the incident broke.
His Super Rugby team the Auckland Blues, who play the Otago Highlanders at Eden Park later on Friday, said earlier in the week that they fully supported his absence and trip to Christchurch.
"I think it's admirable, really," assistant coach Tom Coventry told reporters on Thursday.
"His faith is strong. He felt for the people of Christchurch.
"We admire what he's standing for and the fact that he wants to go there and grieve and be part of the support for the region and people of New Zealand. He has our best wishes."
Numerous All Blacks players have demonstrated their support for New Zealand's Muslim community throughout the week, including captain Kieran Read, scrumhalf TJ Perenara, lock Sam Whitelock and flyhalf Beauden Barrett.
All Blacks coach Steve Hansen, who lives on the outskirts of Christchurch, said on Friday that the way New Zealand reacted could set the standard for the rest of the world to follow.
"What we need from every individual from our country is calm heads and loving minds and coming together and understanding that we've got to respect each other and love each other and care for each other," Hansen told The New Zealand Herald
"If we can all do that it doesn't matter what colour our skin is or what religious beliefs we have, we'll lead the world."
(Reporting by Greg Stutchbury; Editing by Nick Mulvenney)
