"The summit was held in an extremely friendly atmosphere ... and the results should be considered as a huge achievement and a turning point in the history of cooperation between the five Caspian Sea states," Ahmadinejad said at the closing ceremony of the summit.
The final agreement on the legal status of the Caspian see left to the next talks.
"I here proclaim that the Caspian Sea is and will forever remain the sea of peace and solidarity among the littoral nations", Ahmadinejad said.
He said that the summit also emphasized respecting the Nuclear Non-Proliferation Treaty (NPT) and the rights of all NPT signatories and International Atomic Energy Agency (IAEA) member stats to have the right to pursue peaceful nuclear technology "without any discrimination".
Putin had called earlier Tuesday for a "balanced" solution to the legal status of the Caspian Sea, in dispute since the collapse of the Soviet Union in 1991.
"We have to try to find a balanced solution acceptable to all sides and to make the best out of the status quo of the Caspian Sea even before agreeing the legal status," Putin said through an interpreter.
"We have to build confidence to settle the relevant issues and not even think of resorting to force against each other in the Caspian Sea, or allowing other countries to avail themselves of our (Caspian) territories," the Russian president added.
"A joint understanding and use of the Caspian Sea and its oil, gas and biological resources regardless of national bounds will be to the benefit of all littoral states," he told the summit.
Speaking to the press following the summit, Putin also termed the talks as positive and said that the agreements reached in Tehran should be used as a framework before finalization of the legal status.
He further welcomed the formation of the Caspian Sea economic commission whose first session is to be held next summer in Moscow under his chairmanship.
Kazakh President Nursultan Nazarbayev said that the Tehran summit has been more effective than the previous one in Turkmenistan and had brought the five states closer to resolving the sea's status issue.Meanwhile Ahmadinejad in a reference to an alleged plot to assassinate Putin as the Russian leader was attending the summit criticized "certain elements" whom he said sought to stoke tensions rather than promote friendship between the Caspian Sea states.
During the meeting Putin backed Iran's right to nuclear energy and argued against military action.
Along with the four other Caspian Sea states, Putin signed a statement supporting Iran's right to peaceful nuclear energy.
It backed the right of Non-Proliferation Treaty members to "Research, produce and use nuclear energy for peaceful ends, without discrimination, within the framework of this treaty and the mechanisms of the UN nuclear watchdog." Putin told a news conference.
The countries had "expressed the idea that peaceful nuclear activities must be allowed,"
"Russia is the only country helping Iran to construct a nuclear power station for peaceful ends," Putin added, referring to the unfinished project to build Iran's first nuclear energy plant in Bushehr.
Amid continued speculation over the possibility of a US military strike against Iran, the Caspian leaders also agreed never to allow their territory to be used for an attack on a fellow littoral State.
"The parties emphasize that in no circumstances will they allow their territory to be used by a third country to commit aggression or other military action against one of the parties," the declaration said.
"We are saying that no Caspian nation should offer its territory to third powers for use of force or military aggression against any Caspian state," Putin said.
Iranian President Mahmoud Ahmadinejad also underlined the need to keep outsiders away from the Caspian.
"All Caspian nations agree on the main issue - that all aspects related to this sea must be settled exclusively by littoral nations," he said. "The Caspian Sea is an inland sea and it only belongs to the Caspian states, therefore only they are entitled to have their ships and military forces here."
Putin, whose trip to Tehran is the first by a Kremlin leader since World War II, warned that energy pipeline projects crossing the Caspian could only be implemented if all five nations that border the Caspian support them.
Putin did not name any specific country, but his statement underlined Moscow's strong opposition to US-backed efforts to build pipelines to deliver hydrocarbons to the West bypassing Russia.
"Projects that may inflict serious environmental damage to the region cannot be implemented without prior discussion by all five Caspian nations," he said.
"The Caspian Sea should unite us rather than divide us," Putin told the summit, which groups the heads of state of Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan.
The last Kremlin chief to visit Iran was Soviet dictator Josef Stalin, who attended the famous conference of the "Big Three" World War II Allied powers in Tehran in 1943 alongside Winston Churchill and Franklin D. Roosevelt.