AP WHITE HOUSE CORRESPONDENT

TERENCE HUNT

WASHINGTON (AP)—President Clinton abruptly withdrew a shipload of noncombat troops from Haitian waters Tuesday but warned defiant leaders there he was ‘‘dead serious’‘ about the return of ousted President Jean-Bertrand Aristide.

Clinton coupled his action with an urgent request for the immediate reimposition of U.N. economic sanctions against Haiti, targeted at military and police leaders trying to block Aristide’s return under a U.N.-brokered accord.

‘‘Now the time has come for the people who are clinging to their last gasp of power to honor the agreement,’‘ Clinton said. ‘‘They made the agreement; they’ve got to honor it.’‘

He said, ‘‘I want the Haitians to know that I am dead serous about seeing them honor the agreements they made.’‘

The fast-moving chain of events came one day after the USS Harlan County, an amphibious landing ship carrying about 194 U.S. and 26 Canadian noncombat forces, was blocked from docking in Port-au-Prince by armed toughs protesting U.S. involvement. The troops were on a U.N. mission to train the Haitian military and to engage in construction projects involving roads, clinics and schools.

The ship was sent Tuesday to the U.S. Navy base at Guantanamo, Cuba. A second U.S. ship set to arrive at Haiti on Wednesday, the USS Fairfax County, was ordered not to leave its station at Little Creek, Va.

Kathleen deLaski, the chief Pentagon spokeswoman, said that 25 Americans who arrived in Port-au-Prince last week as an advance team ‘‘will remain there for a short time’‘ but will leave Monday if no significant progress is made in calming the situation at the port, where the Harlan County was unable to land.

The United Nations is trying to put together a 600-man international police force, largely composed of French-speaking members, that would precede any U.S. troops into Haiti, said a congressional source, who spoke on condition of anonymity. Members of the Senate Armed Services Committee were briefed by Pentagon officials late Tuesday.

Secretary of State Warren Christopher accused Haitian Army chief Raoul Cedras and police commander Michel Francois of reneging on commitments last July for a return to democratic rule from military dictatorshi.

‘‘By their actions, Gen. Cedras and Chief of Police Francois are really inviting the reimposition of severe economic sanctions, which would affect their country and also affect them personally,’‘ Christopher said.

International sanctions against Haiti were lifted after the July agreements were signed. But the Organization of American States voted Tuesday afternoon to condemn the Haitian protesters and threaten to reimpose those trade sanctions if last July’s commitments are not honored.

Aristide, after a meeting in Washington with Rep. Joseph Kennedy, D-Mass., said he was confident that international pressure would prompt the military regime to step down on Friday, as scheduled.

‘‘Those killers stopped the process yesterday and their removal is indispensable to the restoration of democracy,’‘ Aristide said.

Clinton said he thought the U.N.-brokered agreement to restore democracy ‘‘will come back to life, but right now it has been abrogated.’‘

The president said there is ‘‘still a chance’‘ of returning Aristide to power.

Clinton drew a sharp distinction between the mission of the 600 noncombat troops headed for Haiti and the role of more than 4,700 forces in a casualty-marred peacekeeping assignment in Somalia.

‘‘This is not peacekeeping. This is not peacemaking. This is about restoration of democracy,’‘ the president said. ‘‘So we are going back to the sanctions until those people do what they said they would do.’‘

Clinton said the Defense Department felt that the U.S. troops’ light arms were sufficient to defend themselves if the agreement were being honored, but he added, ‘‘I am not about to let them land to test it.’‘

The president said that both Aristide and the international community had done their part to develop a plan for democracy but the Haitian military and police were reneging.

‘‘There’s no point in our even trying to land there until we can do what we were asked to do as advisers,’‘ he said.

‘‘They’re going to have to honor this agreement. Otherwise, I’m going to press very hard to have the sanctions’‘ reimposed, the president said.

Christopher expressed confidence ‘‘the sanctions can be very effective in reminding those who are responsible for this setback that they should establish a secure environment.’‘

Christopher spoke during a photo session with career diplomat William Swing, the new U.S. ambassador to Haiti who will present his credentials to Aristide on Wednesday. There has been no U.S. ambassador in Haiti for more than a year.

Aristide, who resides here in exile, is to return to Haiti on Oct. 30 under terms of the Governor’s Island agreement last July.

That agreement led to lifting trade sanctions recommended by the Organization of American States shortly after Aristide was ousted on Sept. 30, 1991. The July agreement also prompted the Clinton administration to restore a number of U.S. visas to Haitians who supported the regime.

In June, the U.N. Security Council imposed a mandatory embargo on oil shipments to Haiti. Haiti’s leaders agreed a few weeks later to restore democracy, and the ban was lifted.