"200 people were arrested on Saturday, 150 on Sunday and around 100 yesterday," Ali-Asghar Naserbakht, a deputy in the Tehran city governor's office, told the reformist-linked ILNA news agency.
Protests have been relatively small in Tehran compared with many parts of the country since the unrest began last Thursday.
"We feel the situation in Tehran is more calm than previous days. Already yesterday, it was calmer than before," said Naserbakht.
He added that no request had yet been put to the Revolutionary Guards to intervene in the capital.
"We will not permit insecurity to continue in any way in Tehran. If it continues, officials will take decisions to finish it," said Esmail Kowsari, a deputy commander for a local branch of the Revolutionary Guards, on state television.
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