Theroux claims Norman Resnicow is flying into angry, violent tirades with other residents in their building, because he's trying to scare them into not testifying on Theroux's behalf.

According to the docs ... Resnicow's repeated verbal assaults are working, he's made them reluctant to testify in the heated feud over renovations at Justin's crib. JT says one resident told him Resnicow's behavior has "reached a very dangerous level for everyone in the building."

Theroux also accuses Resnicow of trespassing on his property in order to harass workers and take measurements to help his case. In the docs, he says his neighbor invited a "disreputable tabloid" into their building in an attempt to publicly embarrass him.

The actor's asking the court for a restraining order to keep Resnicow from harassing, intimidating or threatening anyone who has or may testify on Theroux's behalf, and to stop using abusive language in emails as well.