Zille said the party chose to visit the homestead because neither the president nor Public Works Minister Thulas Nxesi would answer questions in Parliament.
Zille said site inspections were a standard oversight method undertaken by members of Parliament.
"Our primary method of oversight in Parliament is through questions but also through visits. Parliamentarians undertake visits all the time to see how work is taking place … particularly because we weren't getting answers [and] because government is invoking an apartheid-era legislation, the National Key Points Act [to justify it], we went to see for ourselves," she said.
Zille was speaking in an interview on Radio 702 on Monday, alongside Zuma's spokesperson Mac Maharaj.
On Sunday, a small group of DA leaders, accompanied by members of the media, were prevented from carrying through their plan to deliver letters from Limpopo school children to Zuma's residence, as well as a site inspection of the complex. ANC supporters had gathered on the road to the complex, and police had set up a roadblock.
The DA has given Zuma 72 hours to respond to questions about the development at Nkandla. It has threatened to take government to court if details on the purported quarterbillion rand spent at Nkandla are not provided by the end of Wednesday.
She denied the event was an act of provocation.
"Seven people coming to see how public money is spent, who were elected by voters, is not an act of provocation. What is a provocation is spending R240-million on a private home. That is provocation."
She said the group did not intend to trespass on Zuma's property but went to see "what R248-million buys you".
But Maharaj said the DA had a "strange way of dealing with the presidency".
He said the party wrote to the presidency in October, saying it intended to deliver letters from Limpopo learners to the president's residence, and the presidency responded saying it should rather make arrangements to deliver the letters to the president's offices at Tuynhuis or the Union Buildings.
"The next thing we heard was on the news, a press release saying they're going to go there on an inspection on the president's [so-called] 'compound' as well as the Nkandla area … and they invited the media to be present," he said.
Maharaj said he found this, and the fact that the 72-hour ultimatum had not been issued to the president himself but was done through the media, "very strange".
"We have to ask ourselves what's behind this. Is she serious about it? Or is she just after publicity?" he asked.
Maharaj said the opposition party adopted a "cowboy style" approach to getting the answers it wanted.
"The matter is under attention, we have supported the investigation of the public protector, we've supported the action being taken by the auditor general," he said.
He also accused Zille of using "language loaded with prejudice".
"She's called the president's house a 'compound', a word used for hostels and migrant workers. She'd never use that for a white person's home."
"The exercise to Nkandla was a publicity stunt and we will not play publicity games with [Zille] and anyone else," he said.