The violent altercation last week that left Senator Rand Paul nursing bruised lungs and broken ribs began with “a very regrettable dispute” between neighbors over a “trivial” matter, a lawyer for the man accused of assaulting the senator said on Monday.

The incident “has absolutely nothing to do with either’s politics or political agendas,” the lawyer, Matthew J. Baker, said in a statement. “It was a very regrettable dispute between two neighbors over a matter that most people would regard as trivial.”

The police charged the man, Rene Boucher, 59, with assault after he admitted to tackling Mr. Paul while the senator was mowing his lawn. Aides to Mr. Paul said on Sunday that the Kentucky Republican had suffered five broken ribs and bruises to his lungs. And as the rest of the Senate returned to Washington on Monday, it remained unclear when Mr. Paul would be back at work.