The property is a home and office for publisher Martin Rynja
Three men arrested in north London on suspicion of terrorism continue to be questioned by police.
They are suspected of attempting to set fire to a publisher's office in Lonsdale Square, Islington.
The publisher, Gibson House, is due to release a controversial novel about the Prophet Muhammad and his child bride, entitled The Jewel of Medina.
The three men were arrested by armed officers from the Metropolitan Police in a planned operation.
The men, aged 40, 22 and 30, were arrested under the Terrorism Act 2000 and are being held at Paddington Green police station.
Two were arrested outside the property in Lonsdale Square, and the third following an armed vehicle stop near Angel Tube station on Upper Street at 0225 GMT on Saturday.
A small fire was put out at the property, which is used as a home and office by publisher Martin Rynja, who is due to publish the controversial book.
Its publication in the US was cancelled in August by publisher Random House, fearing it could offend Muslims.
Random House said then it had been advised the book "could incite acts of violence by a small, radical segment".
At the time, Mr Rynja said there must be "open access to literary works, regardless of fear".
He added: "If a novel of quality and skill that casts light on a beautiful subject we know too little of in the West, but have a genuine interest in, cannot be published here, it would truly mean that the clock has been turned back to the dark ages."