New York City Transit president Andy Byford thinks handwritten service announcements — like the ones observed by The Post Monday morning at a station in Brooklyn — make the world’s largest subway system “look like a mom-and-pop shop.”

The city buses and subways chief responded via email to a reporter’s early morning tweet showing the turnstiles at the President Street 2 and 5 station in Crown Heights emblazoned with “No Manhattan-bound trains” in chicken scratch.

“Handwritten signs are anathema to me,” the former British railway exec wrote back. “They are an embarrassment, an own goal and they make us look like a mom and pop shop.”

President Street’s northbound platform will be closed through the middle of August, according to the MTA’s website. The southbound platform reopened this week after being closed since May.

The standard 8½- by-11-inch sheets of white paper were the only notice of the closure posted ahead of the turnstile.

Byford added that while “someone tried to be helpful” by informing riders of the last-minute platform closure, “under no circumstances are handwritten signs to be deployed.”

Station managers have since been reminded to stick to official signage.