He said on social media he "strongly condemns" the incident and added that two persons had been detained without giving further details.
A second tweet, in Latvian, said "Such provocations are not allowed, Russia should take appropriate action."
The press secretary of the Foreign Ministry, Gints Jegermanis, told Latvian Radio that nobody was injured in the incident, which took place at around 6 p.m. Moscow time.
Between 4 and 5 people appeared at the embassy's premises in Moscow and set off smoke bombs and flares. One person tried tried to write something to the embassy building, but the militia intervened at this point, Jegermanis said.
Latvia will present a diplomatic note to the Russian foreign ministry over the incident, Jegermanis added.
A video of the incident, apparently shot by the perpetrators, was posted online in Russia and shows the street outside the embassy filling with black smoke before the person doing the filming runs away.