Roosevelt was indicating that he wanted to protect American workers (with unemployment insurance), but was not encouraging that persons receive government handouts as a perpetual way of life ("the dole").
The expression, "being on the dole," came into use in Britain after World War I, as slang for receiving unemployment benefits, or money being "doled out" by the government. Frances Perkins, who became Secretary of Labor for the Roosevelt Administration, recalled how Roosevelt had included that line already in a speech as a candidate for the presidency in 1932. She noted that Roosevelt's words were subtly attractive to voters. When he said, "I am for unemployment insurance but not for the dole," it signaled a commitment of his candidacy toward helping the unemployed. "It created a great interest and a great enthusiasm among the voters," she said, and they worked to get such ideas into the Democratic Party's national platform.
Incidentally, Frances Perkins was the first woman to serve in a cabinet position for the US government.
