They have not yet received other complaints of that nature.
He said police and family were supporting the victim.
"It's pretty traumatic to go through something like this . . . It's really frightening.
"We certainly feel for her and are absolutely committed to supporting her."
Police were "pretty focused on tracking this guy down and holding him to account".
Anyone with information can contact police on 105 and refer to file number 220423/9551, or call Crime Stoppers anonymously on 0800 555 111.
Wellington has recently been grappling with city safety issues and people feeling unsafe when walking the streets at night.
In an unrelated incident on the same weekend of the sexual assault, a gang shooting on Dixon St left two people critically injured.
Seven people have been arrested in relation to the early morning shooting, which police believe is linked to a second shooting hours later in Tawa.
Last weekend, about 100 teenagers were reportedly involved a late-night street fight in Newtown.
About 35 officers were required to clear the area and one person was arrested for breach of the peace.
Local Wellington City councillor Fleur Fitzsimons said the teenagers were out of control and residents were scared for their safety.