WASHINGTON — Grappling with a record death toll in an overshadowed war, President Bush promised yesterday to send more American troops into Afghanistan by year’s end. He conceded that June was a “tough month” in the nearly seven-year-old war.

In fact, it was the deadliest month for American troops in Afghanistan since the conflict began.

“One reason why there have been more deaths is because our troops are taking the fight to a tough enemy, an enemy who doesn’t like our presence there because they don’t like the idea of America denying safe haven” to terrorists, Mr. Bush told reporters. “Of course there’s going to be resistance.”

Mr. Bush said it was a tough month too for the Taliban. But the once-toppled Islamist regime in Afghanistan has now rebounded with deadly force.

More American and NATO troops have died in the past two months in Afghanistan than in Iraq, a place with triple the number of American and coalition forces.

In June, 28 American troops died in Afghanistan. That was the highest monthly total of the entire war, which began in October 2001.

For the full American-led coalition in Afghanistan the death toll was 46, also the highest of the war.