MOSCOW - Israel told Russia it would not launch an attack on Iran, Russian President Dmitry Medvedev said in a CNN interview released Sunday, in which he described such an attack as the worst thing that can be imagined.

Medvedev said Israeli President Shimon Peres made the pledge at a meeting in August. After the meeting Peres said Medvedev had promised to reconsider the sale to Iran of S-300 anti-aircraft systems that would complicate an Israeli attack.

Israel has hinted it could forcibly deny Iran the means to make an atomic bomb if Tehran continues to refuse to suspend uranium enrichment it claims is for peaceful purposes.

When he visited me in Sochi, Israeli President Peres said something important for us all: 'Israel does not plan to launch any strikes on Iran, we are a peaceful country and we will not do this', Medvedev said in the interview, which was recorded on Tuesday, according to a Kremlin transcript.

An attack would lead to a humanitarian disaster, a vast number of refugees, Iran's wish to take revenge and not only upon Israel, to be honest, but upon other countries as well.

But my Israeli colleagues told me that they were not planning to act in this way and I trust them, he said.

Asked about the possible delivery of S-300s, Medvedev said Russia had the right to sell defensive weapons to Iran. He said sanctions are often ineffective and no action should be taken against Iran, except as a last resort.

The chances of an agreement with the United States on a new treaty to reduce strategic offensive weapons by the end of the year remain quite high, Medvedev said.

(Writing by Conor Humphries; Editing by Sophie Hares)