The arrests, which took place in various cities across the county, follow approximately 150 detentions last month.
Zoe Smith, head of advocacy at Open Doors UK - a charity which speaks out on persecution against Christians - described the news as "highly concerning".
She said: "It follows an established trend of the Iranian government - as the number of converts to Christianity increase, so the authorities place greater restrictions on churches".
"The restrictions are worse for churches seen to be attended by Christians who have converted from Islam.
Please pray for a safe and peaceful #Christmas for believers in #Iran like Nava*, who must celebrate the birth of Jesus in secret for fear of being imprisoned - or even sentenced to death. #PrayWithThem— Open Doors UK ن (@OpenDoorsUK) December 6, 2018
*Name has been changed for security reasons
"Not only that, but the government is asking unreasonably high bail amounts and seeing longer prison terms for Christians."
Most of the detainees were freed within hours or a few days but not before their mobile phones were confiscated.
They were questioned on their involvement in Christian activities and told to expect a call from Iran's Ministry of Intelligence.
Open Doors fears officials are clamping down on the Church in Iran as it continued to grow.
It warns long prison sentences are becoming an increasingly common reality - even for believers who have never been arrested before.
Zoe Smith from the organisation added: "Some Christians disappear from their communities after serving a sentence; church leaders are put under pressure to leave the country or face an arrest; house churches weaken as their members choose to decrease their meeting hours and minimise their activities; some Christians lose the contact with their churches altogether becoming isolated."
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