Iran's revolution leader:

"All the lands of Karabakh must be returned to Azerbaijan, of course while preserving the safety of the Armenians in it. The terrorists should not approach our borders and if we feel in danger, we will take the necessary measures."

In this statement he strictly discussed the matter of the lands that are owned by Azerbaijan but are currently under Armenian control.

This stems from the UN resolution and the fact that even Armenia hasn't officially annexed those lands yet.

This relationship between Armenia and Artask is the same reason why Russia, who has a joint military agreement with Armenia, didn't take a side and effectively help Armenia.

Both Russia and Iran fear a war there and are trying to end this. Turkey and Israel are fueling it.

The statement has nothing to do with Khaminai's Azeri origins or religion

Iran's strategic position has to do with the attempt to prevent escalation. Preventing escalation means preventing external interference in the Caucasus, especially by the Israeli side which is close to Az

Add to that Iran has a large population of Azeris and Armenians and can not handle a direct war between both countries because it will backfire into Iran and cause ethnic clashes.

That's why Iran and Russia have already presented several proposal to end this war.

Azerbij itself is not close to Iran as the rulers there are against Iran's foreign policy and have for several times imprisoned those who worked with IRGC

The Azerbaijan system even tends for force secularism and have fought the freedom of practicing the religion of the majority

The auxiliary forces are called husayniuwn.

Therefore the statement is not a support of the war effort against Armenia, an Iranian ally, in the favor of Azerbijan but rather simply the position of Iran on who according to UN SC owns that part of the land.