WASHINGTON, April 1 — President Bush, under rising criticism for his handling of the growing violence in the Middle East, expressed frustration today that Yasir Arafat, the Palestinian leader, has failed to denounce what he called the "constant attacks" of suicide bombers.

Mr. Bush, his voice tinged with resentment during brief comments in the Oval Office this morning, also grew testy about suggestions that he had kept his distance from the conflict. He said those who maintained he was insufficiently engaged "must not have been with me in Crawford when I was on the phone all morning long talking to world leaders."

Despite protestations that he has immersed himself in the search for an end to the bloodletting in the Middle East, the president has yet to talk directly to Mr. Arafat, and has not been in direct contact with Prime Minister Ariel Sharon of Israel in recent days, perhaps out of concern that his calls for restraint would be defied by both leaders.

Today, he once again urged Mr. Sharon to keep "a pathway to peace open," but he made no mention of the United Nations resolution calling for Israel to pull its forces back from Ramallah, the West Bank town it has sealed off and where it has placed Mr. Arafat's headquarters under siege. The United States voted in favor of that resolution on Saturday.

Over the weekend, Mr. Bush was assailed by critics who say that he has not been active enough in Middle East diplomacy. They say that it is not enough to simply repeat that Mr. Arafat has to show "100 percent effort" to stop suicide bombings and that Mr. Sharon has to defend his country, but with restraint.

At the same time, some in Congress like Senator Joseph I. Lieberman, a Connecticut Democrat, and Senator Arlen Specter, a Pennsylvania Republican, say Mr. Bush has not committed enough of his time, energy or prestige to the peace effort.

"I believe that the president does have to get more deeply involved," Mr. Specter said.

Secretary of State Colin L. Powell called Mr. Sharon again today, officials said, urging him to think carefully about the consequences of Israeli military action and the wisdom of isolating Mr. Arafat. That call seemed to reflect the feeling of the secretary's Middle East experts that the crackdown in Ramallah and the attack on Mr. Arafat's headquarters would fail to stop the bombings or bring the Palestinian leader to the negotiating table.

Secretary Powell reiterated that Gen. Anthony C. Zinni, the president's special envoy, would remain in the region to help work toward a cease-fire.

While Mr. Bush and his aides have laid the blame for the latest increase in violence on Mr. Arafat, they have so far proposed — at least in public — no new ideas beyond some vague suggestions that the United States might contribute "monitors" if a cease-fire can be negotiated.

Today, the administration even took one option off the table: American peacekeeping troops to enforce a any peace settlement.

Mr. Specter has said the administration has been considering sending peacekeepers as part of an overall Middle East settlement. Vice President Dick Cheney had previously been careful not to exclude the possibility, saying the issue needed to be discussed first with Mr. Bush, and some experts have said they could be an essential element of a deal.

But Defense Secretary Donald H. Rumsfeld said that he had spoken with Secretary Powell today about the matter and that both agreed that no American peacekeepers would be offered.

Meanwhile, some members of the administration have been quietly searching for ways for the United States to restrain Mr. Sharon's military action without undercutting American support for Israel.

While the administration generally spoke with one voice on the issue, there were subtle differences in emphasis. The White House stressed a need for Mr. Arafat to stop terrorist attacks. The State Department made more of a point of a need for the Israelis and the Palestinians to show restraint.

At the Pentagon, Mr. Rumsfeld put the blame on Iraq, Iran and Syria, which he said were encouraging terrorist attacks by the Palestinians. He declined to comment directly on the effectiveness of the Israeli campaign but cast the Israeli response sympathetically in the context of the war against terrorism.

"When the United States is hit by terrorist attacks, you have a choice," Mr. Rumsfeld said. "You can say, `Gee, that's too bad,' or you can go try to find the terrorists and do something about it. And it seems to me that in our case, which I know a good deal more about than I do that case, it seems to me it's a pretty clear answer."

Mr. Bush and his aides also disputed today that they had provided an exception for Mr. Arafat to the "Bush doctrine," which calls for the ouster of any leaders who sponsor terrorism or harbor terrorists. "Chairman Arafat has agreed to a peace process," Mr. Bush said, defending his continued efforts to deal with him, but deflecting the question of whether Mr. Arafat is encouraging the terrorist acts.

He added later, "He has negotiated with parties as to how to achieve peace."

But clearly the administration is sensitive to criticism that it has created two tiers of the Bush doctrine, one for Al Qaeda and another for Mr. Arafat and his Palestinian Authority. A senior administration official called a reporter today to argue that "we've been treating Arafat just like everyone else — telling him he has to deal with terrorism."

The official said that if Mr. Arafat refused to respond to Mr. Bush's demand that he renounce terrorist acts, "at some point in the future you have to come to the conclusion" that he should be dealt with more harshly.