Russia says downing of Turkish plane not provocation

* FM Lavrov says to attend weekend meeting on Syria

* Says Iran's participation crucial to success of meeting

* Moscow says no alternative to Annan peace plan (Updates to add Putin's comments in Amman)

By Gleb Bryanski and Alissa de Carbonnel

MOSCOW/AMMAN, June 26 (Reuters) - Russia said on Tuesday Syria's shooting down of a Turkish warplane should not be seen as a provocation and warned world powers against using the incident to push for stronger action against Damascus.

It was Moscow's first reaction to Friday's downing of a Turkish military aircraft by Syrian air defences, which gave a new international dimension to the worsening conflict in Syria.

Turkey's NATO allies condemned Syria's action as unacceptable but stopped short of threatening any military response. Turkey also plans to approach the U.N. Security Council.

"It is important that what happened is not viewed as a provocation or a premeditated action (by Syria)," Russia's foreign ministry said in a statement on its website.

Moscow repeated its calls for restraint, warning that any political escalation would be "extremely dangerous" and threaten international efforts to salvage a moribund six-point Syrian peace plan drawn up by U.N.-Arab League envoy Kofi Annan.

"Once again, we call on all sides to act exclusively in the interests of such an agenda (the peace plan) and not to take steps that go beyond its limits," the ministry said.

"We believe that the best course of action is restraint and constructive interaction between the Turkish and Syrian sides in order to clarify all the circumstances of the incident."

Syria provides Moscow with its firmest foothold in the Middle East, buys weapons from Russia worth billions of dollars, and hosts the Russian navy's only permanent warm water port outside the former Soviet Union.

Russian Foreign Minister Sergei Lavrov said he would attend a meeting on Syria that Annan is trying to arrange on Saturday but suggested it would not produce results without the participation of Iran, a close Syrian ally.

"Iran must be present. Otherwise the circle of participants will be incomplete and will not gather everybody who has influence on all Syrian sides," Lavrov told reporters, on the sidelines of Russian President Vladimir Putin's visit to Jordan.

Annan has also said Iran should attend, but diplomats say the United States, Saudi Arabia and others objected to the idea.

Putin later on Tuesday also voiced support for involving Iranian officials in talks seeking an end to the violence, saying it would be "counterproductive" to neglect Syria's neighbour in negotiations to resolve the conflict.

"The more Syria's neighbours are involved in the process the better because almost every neighbouring country has some influence on some forces inside the country," Putin said.

"It is better to involve Iran in this conflict resolution, receive its support," he said.

Russia has used its power of veto in the U.N. Security Council to shield Syria from harsher international sanctions over Damascus's crackdown on the 16-month-old revolt.

Moscow has backed Annan's plan, insisting it is the only way to end the bloodshed in Syria and arguing firmly against any kind of military intervention.

So far Annan's attempts to get the Syrian opposition and government to begin talks aimed at ending the conflict have failed, but he is pushing for a meeting of key regional players and permanent U.N. Security Council members in Geneva on Saturday, hoping to kickstart political negotiations. (Reporting by Gleb Bryansky in Amman and Alissa de Carbonnel in Moscow, editing by Andrew Heavens)