Lobbying for the MX missile, President Reagan insisted yesterday that "I do want arms control," and dismissed suggestions that his commitment isn't sincere as "amateur psychoanalysis."

"I can't believe that this world can go on . . . with this kind of weapon on both sides, poised at each other, without some day some fool or some maniac or some accident triggering a war that is the end of the line for all of us," Reagan told a group of business executives at the White House.

Reagan said the United States must build up its strategic forces to put pressure on the Soviet Union to negotiate arms reductions and maintain peace.

The session with the business executives was the latest step in a drive by Reagan to win congressional approval of funds for the 10-warhead nuclear MX.

Meanwhile, in a counterattack, two former directors of the CIA warned that deploying the MX would put a hair-trigger on nuclear war because both the United States and Soviet Union would be tempted to fire first for fear of losing their missiles to such a silo-busting weapon.

William E. Colby and Stansfield Turner, CIA directors in the Nixon and Carter administrations, respectively, sounded that warning in a news conference called by Sen. Gary Hart (D-Colo.), one of six announced contenders for the Democratic presidential nomination, to launch what he called "a national mobilization to stop the MX missile."

Congress should "get rid of this particularly dangerous weapon and put to rest any prospect that we would go for a first-strike strategy," Colby said.

The Soviets, Turner said, would be "nervous" about the possibility of the United States launching the MX against Soviet targets.

"They will have to have their finger on the trigger," he said, to guard against losing their missiles to a first strike, while the United States will have to do the same thing for fear of losing the MX in a surprise blow.