Obama offered "warmest wishes for a sweet and happy New Year, and recalled a quote by his "good friend" Ellie Wiesel which emphasizes the importance of renewal: "God gave human beings a secret, and that secret was not how to begin but how to begin again."
"These days of awe are a chance to celebrate that gift, to give thanks for the secret, the miracle of renewal," Obama said.
The US president said "we continue to stand against the scourge of anti-Semitism" and reiterated his country's commitment to its "unshakable alliance with the State of Israel."
"From my family to yours, shana tova," concluded Obama.
Cameron's greeting also include a message on Yom Kippur, wishing Britain's Jews "G’mar Tov and Shana Tova."
Cameron also discussed the importance of Britain's Jews. "These High Holy Days give us a chance to look back – and to look forward. To look back at the immense contribution Jews make in Britain: excelling in every field, contributing in every community, and living by those values – of decency, tolerance, hard work and responsibility – that are so central to the Jewish faith and to British life.
"And they give us a chance to look forward to a future free from conflict and prejudice. That means lasting peace in the Middle East – a future where families don’t live in fear of rocket attacks. And it means wiping out prejudice in this country, because we will not tolerate anti-Semitism in Britain. No disagreements on politics or policy can ever justify racism or extremism in any form," the British premier said, vowing to continue tackling anti-Semitism in the country.