Social Development Minister Anne Tolley "felt sick" when she heard about the failed arson attempt her electoral office in Whakatane overnight.
Three Molotov cocktails were thrown through the glass door of the office, smashing the window, but it didn't catch alight.
She surveyed the damage this morning.
"It's a really determined effort, there's a lot of thought gone into it so we've got reinforced glass in the door and they've had to smash that and maybe even cut the wires to get the Molotov cocktails through."
Anti-TPP and John Key graffiti was also scrawled on the mural outside the office.
Ms Tolley has told the Prime Minister about it the incident after she heard about it.
"I let him [John Key] know that I was okay because I've had all my colleagues calling and making sure that we're okay and that our staff are okay because this is their workplace to think that someone wanted to burn that down is just horrible, it really is horrible."
Ms Tolley doesn't believe there's any excuse for violence.
"Lots of people feel passionately about things, but they don't resort to violence. Violence is never the answer for anything and there's always the opportunity to talk through issues, we're not necessarily going to agree but violence is not the answer and too many people in our communities feel that if things don't go their way or if they don't like something they resort to violence, that's why our family violence statistics are so bad."
Mr Key says people have the right to peaceful protest as long as they don't break the law.
"Incidents like these are hugely disappointing because our MPs work incredibly hard for their communities as do the staff who work in their offices. They have a right to feel safe in their workplaces and I would urge people to respect that."
Police were called to the office on The Strand just after 6am.
Police are still outside the office standing guard, and there are scorch marks on the door.
The area has been cordoned off as fire investigators assess the situation.