In comments carried by Kargozaran newspaper, Khamenei also warned during a meeting with Ahmadinejad and his cabinet against undermining the government, which has faced intense criticism over inflation which has topped 26 percent.
Khamenei backed Ahmadinejad's economic initiative, mainly aimed at redirecting billions of dollars of state subsidies towards lower income groups, but also cautioned against its hasty implementation.
"If part of this plan fuels inflation, a way must be found to prevent this or control any negative aspects," he said, nonetheless describing the plan as an "important job which definitely has to be carried out."
In an apparent comparison with the reformist presidency of Mohammad Khatami, he also praised Ahmadinejad's government for "blocking dangerous trends of Western intoxication and secularism which were infiltrating the country's administration."
The all-powerful leader said previous administrations had his backing as well, "but the current government's characteristics mean it has warmer support."
"Denying its positive aspects and highlighting weaknesses and constantly speaking against it is sabotage, not criticism," Khamenei said.
Many economists blame Ahmadinejad for fuelling inflation by ploughing huge amounts of cash into local infrastructure projects.
There has been a sharp increase in money supply growth — an annual indicator of inflation trends — which reached nearly 39 percent in a year under Ahmadinejad.
The president, whose term ends in a year, ran a bread and butter campaign in 2005 vowing to make the poor benefit from Iran's oil wealth.
He has faced mounting criticism from reformists and many fellow conservatives over his handling of the economy, with several top clerics also calling on him to control soaring prices.
