Prime Minister Benjamin Netanyahu will not give up on his demand that red lines be placed before Iran, a senior diplomatic source told Israel Hayom on Wednesday. "Without red lines there is no reason [for the Iranians] to cease their pursuit of a nuclear weapon," said the source.

Despite the prime minister's one-hour phone call with U.S. President Barack Obama on Tuesday night, tensions between Jerusalem and Washington were apparently still running high.

Speaking ahead of a meeting with Bavaria's Minister-President Horst Seehofer on Wednesday, Netanyahu said: "We are facing great challenges. As prime minister of Israel, it is my duty to uphold the vital interests of the State of Israel, to ensure its security and its future. The greatest interest today is to prevent Iran from continuing on its clear steps to achieving nuclear weapons, this from a country that calls for our destruction and intends to achieve its goal. I uphold these interests, not that it's easy, because leadership is tested in upholding them even if there are disagreements with friends, even the best of friends. This is what I have done and this is what I will continue to do for the State of Israel and the security of its citizens."

The telephone conversation between Obama and Netanyahu after midnight on Tuesday was, according to an Israeli source, "long [and] frank, and dealt with all of the essential issues."

Vice Premier Moshe Ya'alon also touched on the matter of issuing clear red lines to Iran, saying Wednesday, "The United States has outlined a red line that the Iranians are happy with. There have been arguments with the Americans in the past as well, as was the case during Operation Defensive Shield [Israel's large-scale military operation in 2002 during the course of the Second Intifada] when they asked [former Prime Minister] Ariel Sharon to halt the operation and only later understood it was the right thing to do."

Netanyahu held another conversation, albeit a more comfortable one, with Canadian Prime Minister Stephen Harper on Wednesday. Netanyahu thanked his counterpart for his decision to expel Iran's diplomats and shut down the Iranian Embassy in Canada.

"Your decision constitutes an example of leadership and morality," Netanyahu told Harper. "It is an example of the correct message that the international community needs to send to Iran."

Meanwhile, U.S. Ambassador to Israel Daniel Shapiro said Wednesday that his country was dedicated to Israel's security. "Our commitment is unwavering and the United States will help Israel with any threat it is faced with. We will not let the nuclear threat become a reality," he said.

Shapiro made the comments at his Herzliya residence during an event to toast the new Jewish year. He added, "The bonds between the U.S. and Israel are very strong, but our work is unfinished and we must find new ways to deepen our knowledge, to deepen our cooperation, to strengthen and improve our communication, in private and in public."