The U.S. State Department on Friday called on Israel and Turkey to cool their tensions over Israel's raid on an aid flotilla to Gaza last year which killed nine Turkish nationals.

"We are urging both sides to refrain from rhetoric or actions that could be provocative, that could contribute to tensions," State Department spokesperson Victoria Nuland told reporters.

"Obviously, we would like to see both sides cool it and get back to a place where they can have a productive relationship," she said.

"We want to see these two strong allies of the United States get along with each other and work together in support of regional peace and security," Nuland added.

A long-awaited UN report investigating the raid on the flotilla heading for Gaza said last Friday that Israel's naval blockade of the Gaza Strip was legal and appropriate, but that the raid of the flotilla was "excessive and unreasonable."

In a furious response to the Jewish state's refusal to apologize for the deadly attack, Turkey decided last Friday to downgrade the Turkish-Israeli diplomatic relations to the level of second-secretary and suspend all military ties with Israel.