The OSCE, of which Russia, the European Union and the U.S. are all members, agreed to the six-month deployment on Friday.
At first 100 monitors will be sent around the country. But Russia's OSCE envoy, Andrey Kelin, said they will not be given access to the Crimean peninsula.
"They have no mandate there," he said of the Black Sea region, which was formally annexed by Russia on Friday, less than a week following a referendum in which the people of Crimea voted overwhelmingly to join Russia.
Despite the comments, Russian Foreign Ministry spokesman Alexander Lukashevich said in a statement that Moscow hopes the team "will help to overcome the internal Ukrainian crisis" and ensure the respect for human rights there.
The Kyiv-based mission may later expand by another 400 personnel. It will initially be deployed in nine places outside the Ukrainian capital, including Donetsk, a major city in largely Russian-speaking eastern Ukraine.
The text of the decision mentioned reducing tensions "throughout" Ukraine, but did not specifically mention Crimea, leaving it unclear whether the observers will try to go there.
Canadian PM travels to Ukraine
Canada's Prime Minister Stephen Harper becomes the first G7 leader to witness first-hand the tumult in Ukraine when he visits Kyiv today.
Harper, along with Foreign Affairs Minister John Baird, meets with both the new prime minister and president of Ukraine amid the most ominous eastern European crisis since the Cold War.
Harper is taking a day trip from the Netherlands to reiterate Canada's support to Ukraine.
As he arrived in The Hague on Friday night, he announced new sanctions against Russian officials and the bank that finances them.
The economic restrictions and travel bans cover senior Russian bureaucrats, including the intelligence chief of the Russian general staff and more of President Vladimir Putin's aides and advisers.
The sanctions also forbid Canadian citizens and companies from doing business with Bank Rossiya.