Mayor Michael Bloomberg says if he had known a Brooklyn imam was a character witness for a convicted terrorist he would not have greeted him.

Siraj Wahhaj was among clergy invited to meet the mayor, who shook his hand on Wednesday.

Asked if he regrets it, the mayor said Thursday if he had recognized the man’s background, he would not have greeted him.

Wahhaj was a witness for Omar Abdel-Rahman, convicted in 1995 of plotting to blow up city landmarks. Wahhaj was never charged in the case.

As mayor, Bloomberg says he will in general continue to reach out to every group. He believes he was doing that while meeting with Wahhaj, the leader of a large mosque.

MORE: 1993 WTC ‘plotter’ in Mike meet