Representative Luis V. Gutierrez, a Democrat from Illinois who has become a perennial thorn on immigration for President Obama, was arrested Tuesday afternoon along with about a dozen activists in a protest outside the White House.

The protesters were arrested peacefully after they sat down on the White House sidewalk, following a rally where demonstrators denounced the Obama administration for deporting more than one million immigrants in the last two years.

Mr. Gutierrez said he decided to go ahead with the protest after receiving Mr. Obama’s response. “It didn’t disappoint me as much as I was saddened,” Mr. Gutierrez said in an interview after he paid a $100 fine and was released by the police. He was arrested in May 2010 in a similar protest.

In his letter, Mr. Obama argued that immigration authorities had succeeded in increasing the numbers of convicted criminals among immigrants who are deported, while deporting fewer immigrants who lack legal status but have not been convicted of any crime. In 2010, Mr. Obama wrote, 51 percent of deportees were convicted criminals, while 49 percent had noncriminal violations. Two-thirds of the noncriminal deportees had either committed multiple violations of immigration law (which is generally a civil offense) or had been caught at the border soon after crossing illegally, Mr. Obama wrote.

On Monday, in a speech at a meeting of the National Council of La Raza, a Hispanic civil rights organization, the president appealed to Hispanic leaders, including Mr. Gutierrez, to help him pass a broad overhaul of the immigration laws by focusing pressure on Republicans.