Andrew Buncombe, chief US correspondent with The Independent, was detained on charges of failing to disperse shortly after 9am local time on Wednesday, as police in riot gear dismantled the so-called Capitol Hill Occupied Protest (or CHOP) zone close to the city centre.
Despite repeatedly identifying himself as a journalist, Mr Buncombe, 52, was taken to the King County Jail where he was put in handcuffs. He was eventually released after being finger-printed and spending almost 10 hours in custody.
The Seattle Police Department said on Twitter that 44 people had been arrested for alleged offences including failure to disperse, resisting arrest and assault.
Seattle police chief Carmen Best said officers were sent in after the mayor, Jenny Durkan, declared the zone an "unlawful assembly".
Chief Best told reporters: "The CHOP has become lawless and brutal. Four shootings – two fatal – robberies, assaults, violence and countless property crimes have occurred in this several-block area."
She added: "I support peaceful demonstrations. Black lives matter and I too want to help propel this movement forward toward meaningful exchange in our community and meaningful change in our community.
"But enough is enough. Our job is to protect and to serve the community."
Protesters have been occupying the zone as part of demonstrations in support of racial justice following the killing of George Floyd by police officers in Minneapolis on 25 May.
Mr Trump has referred to protesters in the CHOP as "domestic terrorists" and demanded that authorities clear it.
On 11 June he tweeted: "Radical Left Governor @JayInslee and the Mayor of Seattle are being taunted and played at a level that our great Country has never seen before. Take back your city NOW. If you don't do it, I will. This is not a game. These ugly Anarchists must be stopped IMMEDIATELY. MOVE FAST."
The mostly peaceful nationwide protests sparked by Mr Floyd's death have been marked by outbursts of police violence both against demonstrators and journalists.
The US Press Freedom Tracker said that between 26 May and 1 July there had been 112 physical attacks on journalists in the United States, 67 of them by law enforcement, plus at least 64 arrests.
In a report from the CHOP demonstration last month, Mr Buncombe described the occupied area as "a cross between a sit-in, a protest and summer festival" being held in a "rapidly gentrifying neighbourhood known for its buzzy bars and nightlife".
One of those taking part, a personal trainer called Felisha Tyson, told him that the mood felt more like a block party than the "ugly anarchist hell" described by the president. Conservative commentators, however, have pointed to violent incidents - including the fatal shootings of young men aged 19 and 16 - as evidence of a violent or anarchist undercurrent to the protests.