Israel's leader suggested in an interview Thursday that he'll keep publicly pressing the United States to get tougher on Iran, despite the strains his remarks have caused with the Obama administration.

Prime Minister Benjamin Netanyahu's remarks appear to have been aimed at rattling the U.S. into action for fear Israel might otherwise soon attack Iran on its own. But his heightened rhetoric has raised tensions with the White House, and even prompted a leading Jewish U.S. senator to take the extraordinary step of publicly rebuking him.

Netanyahu has repeatedly warned that Iran is getting dangerously close to acquiring a nuclear bomb and has been lobbying Washington for weeks to spell out what conditions would touch off a U.S.-led attack on Iranian nuclear facilities.

In a thinly veiled swipe at the U.S., he said earlier this week that "those in the international community who refuse to put red lines before Iran don't have a moral right to place a red light before Israel."

But Washington, which insists it won't let Iran become a nuclear power, has refused to be specific, despite Israel's implicit threat to act unilaterally if the U.S. doesn't take a tough public position.

The spat has become unusually public, prompting President Barack Obama to phone Netanyahu earlier this week and to follow up the call with a rare late-night White House statement denying reports of a rift. Netanyahu's office has also the two men had a "good conversation."

In a newspaper interview Thursday, Netanyahu suggested he won't abandon his calls for the U.S. to set "red lines, " telling The Jerusalem Post that he was "not exactly shy" about expressing his views on Israel's security interests.

"When I feel I need to speak out, I do," he said.

Iran says its nuclear program is solely for peaceful purposes but Netanyahu is convinced it's a cover to build a nuclear bomb.

The U.S. also suspects Tehran seeks to become a nuclear power, and has been leading international efforts to try to persuade Iran to abandon suspect elements of its nuclear program.

But Washington wants to give diplomacy and tough sanctions more time to try to pressure Tehran. And in a message aimed at Israel, it said several times this week that deadlines or "red lines" are counterproductive.

While Washington has tried to downplay reports of a rift, a leading Jewish U.S. senator who solidly supports Israel took the rare step of publicly criticizing Netanyahu in a letter to the Israeli leader posted on her website.

"I write to you as one of Israel's staunchest supporters in Congress to express my deep disappointment over your remarks that call into question our country's support for Israel and commitment to preventing Iran from acquiring nuclear weapons," wrote Sen. Barbara Boxer, a Democrat from California. "Your remarks are utterly contrary to the extraordinary United States-Israel alliance, evidenced by President Obama's record and the record of Congress."

Israel enjoys strong backing in Congress and it is extremely unusual for its supporters there to question the Israeli government in such an open fashion. Boxer's decision to do so appears to suggest that at least some of his Congressional supporters feel he has gone too far.

Netanyahu spokesman Mark Regev had no immediate comment on the letter.

The possibility of Israel acting alone is a source of concern in Washington because of its potential to set off retaliatory attacks by Iran and its proxies in the region. U.S. officials have made it clear they oppose a unilateral Israeli attack, with the U.S. military chief, Gen. Martin Dempsey, recently saying he would "not want to be complicit" in such an assault.