Voters told NL Times that there were between 100 and 200 people standing in line to vote shortly after the Iranian Embassy in The Hague opened its doors at 8:00 a.m.
Voters who spoke to The Associated Press from the cities of Bandar Abbas, Hamadan, Isfahan, Rashat, Shiraz and Tabriz also described crowded polling places.
On Friday Iranians are voting in the first election since the.
President Rouhani has sought to frame the election as a choice between greater civil liberties and extremism.
Iranians began voting Friday in the country's first presidential election since its nuclear deal with world powers.
Raisi says he will stick by the nuclear deal, but points to a persistent economic slump as evidence Rouhani's diplomatic efforts have failed.
Iran's Supreme leader, Ayatollah Ali Khamenei, cast his vote early and urged Iranians to turn out in large numbers.
He appeared to embrace a more reform-minded role during the campaign as he openly criticized hard-liners and Iran's powerful Revolutionary Guard, a paramilitary force involved in the war in Syria and the fight against Islamic State militants in neighboring Iraq.More news: Trump branded Comey 'nut job' as investigation points at White House
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"Everyone should vote in this important election".
"It's my national responsibility to take part in the elections", said 36-year-old Amin, a resident of Teheran and among Iran's 56 million eligible voters, at a polling station.
Rouhani's staff has claimed he won about 60% of the vote, and fellow reformist Mohammad Khatami released a picture of Rouhani making a victory sign on social media, bragging "hope prevailed over isolation".
But in an apparent reference to the 2009 disturbances, Khamenei has previously warned he would confront anyone trying to interfere in the election.
Economic problems, high unemployment and frustration over the slowness of reforms have plagued Rouhani's presidency, despite the gradual lifting of sanctions.
The decision was made due to unprecedented participation of the people who are still waiting to vote in long queues in Tehran and other cities.
Raisi has blamed Rouhani for mismanaging the economy and has travelled to poor areas holding rallies, pledging more welfare benefits and jobs.
Iran since has resumed crucial oil exports to Europe and concluded billion-dollar deals to purchase passenger planes, but the effects have yet to trickle down to most Iranians, creating an opening for hardliners who feel Rouhani gave too much away.
Whoever wins the presidential vote will influence not only Iran's immediate future but also the battle to choose a new supreme leader, who will rule for life.