The attack happened Monday night, when activists of Drugaya Rossiya threw eggs and smoke bombs at the consulate at Vasilevskij ostrov, 10 linija, 11. They reportedly distributed fliers as well.
An attacker named Stanislav Isaev was detained by the police force on duty by the consulate. He is being charged for 'petty hooliganism'.
Representatives of the unregistered party said that the attack was committed because of Latvia's policy against Russian citizens.
Drugaya Rossiya is an unregistered left-wing party that was founded by writer and opposition politician Eduard Limonov.
A video has been hosted on YouTube with the attack, which shows smoke bombs being thrown at the consulate:
As reported, in June two Russian citizens and members of the Drugaya Rossiya party walked into a massive military exercise in Ādaži, Latvia. They are being charged with terrorism and espionage and could spend up to 20 years in jail.
The Latvian Ministry of Foreign Affairs condemns the attack, BNS reported later.
"We ask Russian institutions to immediately investigate this incident and continue securing the safety of Latvian diplomats and the consulate, as stipulated by the Vienna conventions on consular and diplomatic relations," said Ivars Lasis, Press Secretary of the Ministry of Foreign Affairs.