Estonia has closed its consulate in Moscow after pro-Kremlin youth groups attacked diplomats in protest at the relocation of a Soviet war memorial.
Protests have been held outside Estonia's embassy in Moscow
Estonia's foreign ministry said there was an attempt to physically assault their ambassador at a news conference.
It said the incident amounted to a violation of diplomatic conventions.
Estonians of Russian origin rioted last week after the controversial statue of a Soviet soldier was moved away from the centre of the capital, Tallinn.
One person died and 153 were injured in the unrest.
Estonians say the soldier symbolised Soviet occupation. Russians describe it as a tribute to those who fought the Nazis.
Estonia's ambassador Marina Kaljurand said members of the Russian youth organisation "Nashi" tried to disrupt a news conference she was holding at newspaper offices.
1918: Estonia gained independence from Russia
1940: Forcibly incorporated into Soviet Union
1941-1944: Occupied by Nazi Germany
1944: Soviets return as Nazis retreat
1991: Gains independence as Soviet Union collapses
1994: Last Russian forces leave Estonia
Now: Ethnic Russians make up quarter of Estonia's 1.3m people
Tear gas was used by her body guards to force back about 30 youths, who stormed the building, reportedly shouting: "Fascist Estonia!"
"The consulate's business is stopped and we will not give visas until the situation is normalised around the embassy," Ms Kaljurand said.
Reports said Russian police also scuffled with activists outside the Estonian embassy, arresting one person as protesters attempted to prevent diplomats entering or leaving the building.
The Swedish foreign ministry has meanwhile submitted a formal protest to Russia after its ambassador's car was stopped and damaged by a crowd outside the Estonian embassy in Moscow.
Following the disturbances, the European Union said it would send a delegation to raise concerns with Russia over the increasing violence.
A European Commission spokeswoman said the EU "strongly urged" the Russian authorities to implement their obligations under the Vienna Convention for diplomatic relations.
Tensions have escalated ahead of the World War II Victory Day anniversary on 9 May.
The anniversary is traditionally a day of patriotism and pride for many Russians.
Moscow Mayor Yuri Luzhkov called for "a boycott of all things connected with Estonia", at a May Day rally on Tuesday.
He said Estonia had dismantled the Soviet memorial "in the most barbaric way".
More than a quarter of Estonia's 1.3 million people are ethnically Russian, and speak Russian. However, half of them do not have Estonian citizenship.
During the years of Soviet occupation after the war tens of thousands of Estonians were killed. They say their country was effectively colonised, with many Russians being brought in as workers and military personnel.