Russia's foreign minister rejected Monday any attempt to impose a deadline on the Syrian leadership for complying with a cease-fire and peace plan designed by former United Nations chief Kofi Annan.

Annan, a special envoy on behalf of the Arab League and the U.N., was meeting with the Security Council at the world body's New York headquarters to discuss the progress – or lack thereof – of the peace plan in Syria. He has asked the U.N. to set an April 10 deadline for at least partial compliance with his plan by the regime of Syria's President Bashar al-Assad.

The plan includes an immediate cease-fire by both Assad's forces and  the anti-government rebels it has been fighting for over a year, along with withdrawal of the regime's tanks and artillery from rebel-held civilian areas. The plan doesn't specify a deadline for Assad.

Sergei Lavrov, the Russian foreign minister, told journalists in Armenia: Ultimatums and artificial deadlines rarely help matters. The Security Council will judge who should implement Annan's proposals, and how.”

Lavrov said only the Security Council -- on which Russia is one of five veto-holding members -- can establish a time frame for Assad’s compliance with the Annan plan.

Over the weekend, at a summit in Istanbul, officials from Arab and Western countries indicated they would ask the U.N. to spell out such a deadline. Neither China nor Russia had representatives at that meeting.

Lavrov, on a visit to Armenia's capital, Yerevan, explained that he didn't got to Istanbul because no one from the Syrian government was invited.

We are trying to be friends for all Syrians and not only for one part of the Syrian nation, he said.

In Syria, the bloodshed continued Monday, with at least 18 people dead in the wake of a crackdown on rebel areas of the cities of Homs and Aleppo, and villages in northern Idlib province. At least 9,000 people have died in Syria since the revolt against Assad broke out in March 2011, according to U.N. estimates.