The Reagan administration's new approach to Panama's leader, Gen. Manuel Antonio Noriega, is perceived in Panama as a risky move that may not resolve the country's crisis.

Panamanian government officials and opposition politicians are untypically in accord in describing American policy as contradictory and as offering new maneuvering room to Noriega, which could prolong negotiations for his departure.Noriega's supporters hint that if he does not give in, American officials will feel forced to make further concessions.

"They are negotiating with a guy who has been making deals all his life, a guy experienced in intelligence work," said a Panamanian businessman who supports the ruling, pro-military party. "Noriega is a master of negotiations, he'll sign anything and then do what he wants. I think the Americans don't know what to do about him."

In Central American politics, an adversary who openly threatens to use force against another but then is forced to back down and offers to negotiate is seen as having lost half of the political battle. From this weakened position, any subsequent negotiations are extremely difficult.

That process now appears to be under way in the confrontation between Noriega and the administration. The administration's last strong card is to maintain economic sanctions against Panama to force Noriega out, opposition politicians and American officials here say.

Not surprisingly, the general has made the lifting of sanctions his first condition for agreeing to leave power later this year. Panamanian political analysts say, however, that such a move will allow Noriega to prolong negotiations further in hopes that the administration's position will weaken under the pressure of the presidential campaign in the United States.

An adviser to Noriega spoke of a new "realism" in the administration's dealings with the general.

"They began very arrogantly, very foolishly, trying to order us what to do," the adviser said. "Now there is more flexibility. Maybe in time we can work something out. But there is no hurry."

The adviser noted that the Reagan administration had softened the terms under which Noriega should relinquish control of the military and had also been forced to send a special envoy to negotiate with the general even though he is under indictment in the United States on drug-trafficking and racketeeting charges.

The Noriega adviser said the mission of the envoy from Washington, Michael G. Kozak, a deputy assistant secretary of state, has effectively cut the American Embassy in Panama out of negotiations with the general. He said that this is to Noriega's advantage because in the general's view the embassy takes a harder line against him.

In addition, the general's supporters say, the new American willingness to negotiate shows that the administration itself is now under political pressure to find a solution in Panama. The adviser said he doubted the administration would now intervene militarily in Panama and it cannot tolerate a long standoff amid the criticisms generated by a presidential campaign.

He added that the regime is well aware that there are bitter disagreements among the Pentagon, the State Department and the American Embassy here on policy toward the general and that such divisions are in Noriega's favor.

Finally, the general's supporter noted that a federal judge in Miami has agreed to allow Noriega's lawyer to make an initial defense of the general to contest an indictment against him for drug dealing, without the general himself being required to appear in the court in person.

When told that the Reagan administration had no influence over the federal judge's decision, the adviser expressed disbelief. He was sure, he said, that it was all part of an overall deal being coordinated by the White House.

In Panama, judges are politically dominated by the regime and do what they are told in sensitive cases. It is inconceivable to the general's supporters that the White House cannot manipulate the indictments against him in Miami.