An Abington man accused of striking two children on a crosswalk in Dorchester while driving under the influence of drugs last week pleaded not guilty Friday in Dorchester District Court, Suffolk District Attorney Daniel F. Conley said. Boston police arrived at the intersection of Talbot and Dorchester avenues around 6 p.m. on Thursday where witnesses said a car had struck the children, prosecutors said. The driver, Michael Duca, 28, was visibly intoxicated and failed sobriety tests, said Jake Wark, a spokesman for Conley. Duca was charged with operating after license suspension, operating under the influence of drugs, and negligent operation of a motor vehicle, said Wark. The children injuries not believed to be life-threatening and were taken to Boston Medical Center for evaluation.