According to a report by BBC News, the pro-Georgian blogger, known as Cyxymu, said he had been targeted for 'telling the truth about the Russian-Georgian war' in his writings.
The attack caused a blackout of Twitter for about two hours on Aug 6.
Despite the blogger's claims, security researchers say there is "no suggestion the attack was state-endorsed".
Google, Facebook and blogging platform Live Journal - all sites where Cyxymu had accounts - were also affected.
"I write the truth about the Russian-Georgian war and somebody did not like these truths - these people in Russia," the blogger told BBC News. "I don't know which people," he added.
The blogger, real name Georgy, has posted videos and blogs that criticize Russia over its conduct in the war over the South Ossetia region, which began one year ago.
"It's a big surprise to me that my blog has meant that 250 million people have not been able to enter Facebook," he said.
Graham Cluley, of security firm Sophos, told BBC News there was no suggestion the attack against the blogger was state-endorsed.
"It was almost certainly an individual who took objection to his blogs," he said. "They took internet vigilantism into their own hands to try to blast him off the web, but in the process blasted Twitter off instead," he added.
Facebook had previously confirmed to BBC News that the attacks were directed at an individual who had "a presence on a number of sites, rather than the sites themselves".
"A botnet was directed to request his pages at such a rate that it impacted service for other users," the spokesperson said.
Botnets are networks of computers under the control of hackers.
The machines were used to mount a so-called denial-of-service (DOS) attack on August 6th.
DOS attacks take various forms but often involve a company's servers being flooded with data in an effort to disable them.
"Attacks such as this are malicious efforts orchestrated to disrupt and make unavailable services such as online banks, credit card payment gateways and, in this case, Twitter, for intended customers or users," wrote Twitter co-founder Biz Stone on his blog.
Twitter was knocked out by the attack for around two hours, while Facebook said its service had been 'degraded'. The effect on Live Journal is unclear.