The miscreant, identified as Abid Hussain Saudagar, was traced and arrested from Arampora locality in Nawakadal area, he said.
"The police has arrested a rumour-monger who had spread the rumour about the death of a girl," the spokesman said.
He said the rumour had spread like a "wild fire" last evening.
"Most of the people panicked and a sense of insecurity prevailed all over. People got emotional and started pelting stones at the security forces establishments and vehicles," the spokesman said.
The spokesman said the police investigated the rumour and found it "baseless".