The Ministry of Foreign Affairs recommends avoiding travel to the Russian regions bordering Ukraine due to the increased security threat in the area.
The ministry also advises against traveling to Ukraine and suggests Estonians look for ways to leave the country.
"The situation in Ukraine may change quickly and, as tensions increase, the possibilities for the Estonian Embassy to help citizens may be disrupted," it said in a statement.
Last week, the ministry advised residents to avoid traveling to the country and, if possible, return.
"Due to the worrying situation on the Ukrainian border, the Estonian Ministry of Foreign Affairs is updating its travel warning," it said in a statement.
The warnings were issued due to an increased threat of Russian military action.
The Estonian Embassy in Kyiv continues to operate.
Editor: Helen Wright