Egypt's foreign minister called on the Reagan administration yesterday to play "a reactivated and vigorous role" in the stalled Middle East peace process, warning that "a sense of frustration growing into a sense of despair" would play into the hands of the region's extremists.

Foreign Minister Esmat Abdel-Meguid told a group of scholars, government officials and journalists at the American Enterprise Institute here that Egypt must not be taken for granted.

"We are keen on the friendship of the United States as long as the United States is keen on the friendship of Egypt," said Meguid. "This is a two-way street."

As if to reassure him, the Pentagon announced yesterday that it plans to sell Egypt a fifth aircraft to strengthen its airborne early warning system.

But Abdel-Meguid's remarks were a first public note in a current chorus of voices from representatives of moderate Arab states calling for more U.S. involvement in the search for a Middle East peace. While most public attention in Washington has focused on questions of arms sales and such issues as Israel's economy, Saudi Arabian King Fahd, who is scheduled to arrive in the United States Sunday for a state visit, and Egyptian President Hosni Mubarak, who is coming next month, are expected to press for more U.S. diplomatic and political involvement in the region. Abdel-Meguid is here to prepare for Mubarak's visit.

Moderate Arab leaders have expressed concern at the administration's apparent coolness toward the Middle East since a series of U.S. setbacks in Lebanon a year ago. U.S. officials say that they are waiting for the Arabs themselves to chart new directions in the peace process.

The Egyptian foreign minister offered no markedly new approach to the area's problems. But he did sift some possibilities from the ashes of past initiatives and recent diplomacy that, he warned, must not be allowed to slip past. He suggested various formulations that might give them a chance.

Abdel-Meguid repeated the plea made by Mubarak to President Reagan on the White House steps a year ago, calling on both the United States and Israel to begin a dialogue with the Palestine Liberation Organization.

"You don't need to recognize the PLO," Abdel-Meguid said. "You have to establish a dialogue with it."

He cited what he called the emergence of "moderate leadership" in the PLO since its conference in November in Amman, Jordan, as reason to hope that "a new spirit will prevail on the future course of the organization."

The resumption last year of diplomatic relations between Jordan and Egypt, and Reagan's renewed commitment to his 1982 peace initiative are other "bright spots," Abdel-Meguid said.

Both Egypt and Jordan are attempting to persuade the PLO to adopt the principles, if not the letter, of U.N. Security Council Resolution 242, which calls for Israeli withdrawal from territories it seized in the 1967 war in return for peace within secure and recognized borders.

Abdel-Meguid was reserved when he spoke of Syria's role in the region, criticizing it for helping to divide the PLO, but calling it "an important partner in the peace process."

He said he welcomed a U.S.-Soviet exchange of views on the Middle East. "If this action would lead to reducing the tensions between the superpowers," he said, "why not?"

But Abdel-Meguid's tone was more skeptical when he spoke of the Israelis, "our partners in peace."

While welcoming the announced Israeli withdrawal from Lebanon, Abdel-Meguid said Israel's plans to leave its allied South Lebanon Army in control of the area near its border are not satisfactory.

"We have said to our Israeli friends that we would like to see a real withdrawal and not a cosmetic one," he said.

In this environment of incremental advances and sharp setbacks, Abdel-Meguid said, the United States has "a crucial role to play as the honest peace broker accepted by all the parties."