Police evacuated the commemoration site and carried out searches for explosives hours before the dawn service was due to commence.
Opposition leader Bill Shorten dubbed the news "deeply concerning" and called on Australian travellers to exercise utmost caution in the region.
Mr Shorten said there is no place for violent extremism in the world and praised the dedication of young Australians who travel thousands of miles to pay respect to their dead on April 25 every year.
"We can't let it discourage the marvelous tradition of young Australians travelling to battlefields where Australians have fallen in previous conflicts," he told reporters.
The arrested suspect, a 25-year-old man from Syria, has been taken to a station near the Gallipoli peninsula for questioning.
Turkish security sources told ABC News the planned attack was in reprisal for the March 15 Christchurch mosque shootings.