DUBLIN—Irish Prime Minister Enda Kenny said Wednesday it was time for European Union leaders to "grasp the nettle" of the euro-zone debt crisis, saying that a downgrade of his country's debt to junk status was caused by Europe's failure to respond to the crisis.

Effectively setting a deadline, Mr. Kenny told parliament there "was no point" in him attending a mooted European Union Council meeting Friday if leaders failed to make any decisions in solving the crisis. Action was now needed by euro-zone finance ministers on the...