Iran crossed a red line: Israel PM

Vowing to severely hurt those trying to attack Israel, Prime Minister Benjamin Netanyahu said "Iran crossed a red line", forcing his army to strike its bases in Syria.

Israeli Army and Defence Minister Avigdor Lieberman claimed that the overnight clash, the largest-ever direct clash between the Iranian and Israeli armies, was a setback to Iran's military capabilities by "many months".

The Israel Defence Forces (IDF) said the operation was in retaliation to Iran attacking Israel's northern region with a barrage of rockets.

The army said four of the 20 rockets fired on Israel were intercepted by the iron dome anti-missile system and 16 fell within Syrian territory.

"Iran crossed a red line. We responded accordingly. The IDF carried out a very wide-ranging attack against Iranian targets in Syria," Netanyahu said in a statement.

"No rocket landed in Israeli territory and our policy is clear: We will not allow Iran to establish a military presence in Syria", the Israeli prime minister asserted.

Israel had been bracing for a possible Iranian "revenge" attack after the Islamic Republic accused the Jewish state of having attacked one of its bases in Syria on April 9 in which nine Iranian commanders were said to have been killed.

Tehran accused Israel of having carried out the attack but Israel, as per its known policy, did not accept or deny any responsibility.

On the other hand, Israel has been constantly stressing that it will take all necessary steps to prevent Iran from setting up "forward bases" in Syria to be used to attack the Jewish state.

"Yesterday I delivered a clear message to the Assad regime: Our action is directed against Iranian targets in Syria. However, if the Syrian military acts against us, we will act against it. This is exactly what happened yesterday Syrian military batteries fired surface-to-air missiles against us and, therefore, we attacked them," Netanyahu said.

The IDF "suffered no casualties", either on the ground or in the air, and that no rockets fired from Syria made any impact in Israeli territory, a spokesman said, adding that "all of our planes returned home safely".

As tensions escalated, especially in its northern region bordering Syria, the Israeli Premier called upon the international community to prevent "the Iranian Al-Quds force from establishing itself in Syria".

"We need to unite in order to cut off its spreading tentacles of evil there and everywhere," he said.

"I repeat: Whoever hurts us we will hurt them sevenfold, and whoever is preparing to hurt us we will act to hit them first. This is what we have done and this is what we will continue to do," Netanyahu said in the statement.