Naghi Pirzadeh pleaded guilty in Sydney Central Local Court on Monday to entering the iconic structure and disrupting vehicles.

The 33-year-old appeared in court after spending the night behind bars following his arrest on Sunday morning.

The court heard Pirzadeh, an Iranian national, was forced to flee his homeland after he stood up to the "oppressive regime" and was beaten as a result.

Lawyer Michal Mantaj said his client climbed the bridge and unfurled the flags of the United States, Israel and Australia in an attempt to unite them against Iran.

Pirzadeh parked his ute on the bridge about 6.15am on Sunday before taking out a ladder and climbing onto one of the arches, leaving his ute blocking a lane, according to the agreed facts.

When he was atop the bridge he attached the flags as well as two banners supporting the Restart movement which aims to overthrow the regime of the Islamic Republic of Iran.

In a video posted to Twitter, Pirzadeh can be seen on the bridge in a yellow high-vis vest, addressing US President Donald Trump, Secretary of State Mike Pompeo and "all American people".

"President Trump, I have a message from (the) Iranian people to you," he says.

"At the moment we don't have any president in Iran. Our president at the moment is President Trump. You are our president at the moment until we get (a) new president and we get rid of this terrorist regime."

Wearing the same clothes as in the video, Pirzadeh appeared in court via video link on Monday. He cried and rocked back and forth with his hands clasped in front of him as if in prayer.

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Mr Mantaj said his client's night in prison had a "profound" effect on him and Pirzadeh had broken down in tears when they'd spoken on Monday morning.

"He has now come to an understanding of the fact that the right to freedom of political expression ... in Australia comes with certain responsibilities."

Sunday was the second time Pirzadeh was arrested for climbing part of the Sydney Harbour Bridge.

He was caught inside the structure's southern pylon in December 2017 and charged with two offences for which he received an 18-month good behaviour bond.

Magistrate Robert Williams on Monday sentenced Pirzadeh to a nine-month intensive corrections order and banned him from going within five kilometres of the bridge.

The magistrate also re-sentenced him for the previous two offences slapping him with more than $1200 in fines.

Outside court, Mr Mantaj said his client wished to apologise to the Australian people and police for any disruptions he may have caused.

"Whilst he remains passionately committed to his cause, he's determined that in future he will find ways of expressing his views in ways that are consistent with Australian values and laws," he told reporters.

AAP

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