CARACAS, Venezuela — Risking arrest, Venezuela’s opposition leader attended a rally on Friday in his first public appearance since he declared himself president, and told supporters to maintain pressure on the authorities “if they dare to kidnap me.”

The rally in eastern Caracas, where at least 500 people converged in a square ringed by police officers, was peaceful and orderly, and there was no immediate indication that the opposition leader, Juan Guaidó, would be taken into custody, as many had feared.

At the same time, President Nicolás Maduro, who had been furiously describing his adversary as the lackey of an American-backed coup plot, appeared to take a more conciliatory approach, calling for dialogue.

Alluding to reports of clandestine meetings that had taken place between opposition members and people in Mr. Maduro’s orbit, he even expressed a willingness to attend such meetings himself. “If I have to use a hood or go naked, however I have to go,” Mr. Maduro said at a news conference.