President Reagan met with Lebanese special envoy Saeb Salam yesterday, and Salam said afterward that the president had assured him that he has "no reverse gear" in his determination to see all foreign forces withdrawn from Lebanon.

The White House meeting came shortly after five American Marines were wounded in Beirut and a day after Israeli Foreign Minister Yitzhak Shamir left Washington with new U.S. proposals that he said had convinced him a withdrawal agreement can be achieved.

Secretary of State George P. Shultz consulted separately yesterday with the Lebanese delegation headed by Salam and Foreign Minister Elie Salem. Both were received at the White House yesterday for a 30-minute meeting with Reagan and an additional half-hour with Vice President Bush.

In remarks to reporters afterward, they made clear their satisfaction that the United States had continued to insist that all Israeli, Syrian and Palestine Liberation Organization forces must leave Lebanon. U.S. officials also made clear that it considers Israel's desire to leave a residual force in southern Lebanon an infringement of Lebanese sovereignty and a threat to the authority of President Amin Gemayel's government.

To assuage concerns about possible future terrorist attacks from Lebanon against Israel's northern borders, Shultz proposed a series of assurances that would involve the United States in training Lebanese units to guard against infiltrators and other measures to create a security zone in southern Lebanon.

These were the ideas taken back to Jerusalem by Shamir. U.S. officials now are awaiting the reaction of Prime Minister Menachem Begin's government to assess whether a withdrawal accord is imminent.

A senior administration official, who spoke with reporters at the White House yesterday on condition he not be identified, said the three-way talks here had produced "a changed situation." He added that, in the U.S. view, the situation has shown progress but is still not at the point of a breakthrough.

The official also said that Reagan's special Middle East representative, Philip C. Habib, and the special U.S. representative to the Lebanon talks, Morris Draper, will return to the area this weekend.

Salam voiced regret at the wounding of the Marines and, in an allusion to speculation that it was caused by Iranian extremists in Beirut, said, "I don't think it came from Lebanese quarters."

The senior official said that the danger of such incidents had been present throughout the time the Marines have been in Beirut as part of a multinational force. But he said the United States does not intend to abandon its commitment to the force.

"I'm not going to tell you there won't be additional incidents," he said. "There are those who want to screw things up, who do not want to see Lebanon made whole again."

Echoing remarks made by administration officials Tuesday, he said the United States believes the Lebanese army is capable of maintaining security in southern Lebanon.