Iran’s national police chief issued a stark warning to the country’s opposition on Friday, saying that the era of “mercy” was over and that the authorities would begin cracking down more harshly not only on street protests but also on anyone who used cellphones and e-mail messages to publicize them.

The police chief, Ismail Ahmadi Moghaddam, said at a news conference on Friday that those who used e-mail and cellphones to organize protests would be punished even more severely than the protesters themselves.

“After all the evidence we saw on Ashura, our tolerance has come to an end, and both the police force and the judiciary will be confronting them with full force,” Mr. Ahmadi Moghaddam said, according to Iran’s semiofficial news service ILNA.