(CNN) - The Secret Service said an unidentified man was arrested Thursday at the White House after running at the vehicle carrying former Republican presidential candidate Mitt Romney to a lunch there.

The man reached into Romney's open vehicle window as the SUV stopped at a White House gate. He was yelling the candidate's name when he was hauled away, apparently by a security officer.

"This afternoon an individual interfered with a motorcade," the Secret Service said in a statement. "He became combative with uniformed Secret Service agents, and was arrested for assault of a police officer and unlawful entrance."

The individual did not appear to physically contact Romney.

Romney was visiting the White House for a lunch with President Barack Obama. The White House said in a statement the "focus of their discussion was on America's leadership in the world and the importance of maintaining that leadership position in the future."

– CNN's Matt Hoye and Gregory Wallace contributed to this report