The activists, who are based in the United States and Europe, made their call in an open electronic message to RFE/RL and posted on Iranian news websites.
Signatories said Iran's rulers are trying to regain legitimacy inside the country through their confrontation with the international community. They added that Iranian authorities are domestically using the threat of a foreign attack on the country as a tool to increase their repression of those seeking freedom.
"We view the continuation of the current deadlock, Iran's nuclear ambitions and the empty show of force by the establishment as increasing the likelihood of a military action and the people of Iran will be the main victims," the message says.
Washington-based political activist Ali Afshari, who helped write the letter, told "Persian Letters" that activists inside Iran were not asked to sign the letter because of potential security risks.
He said he believes some of the demands raised in the letter could have the potential backing of some democracy activists inside the country.
The letter says making the call for the suspension of uranium-enrichment activities a priority along with respect for human rights, basic freedoms, and democracy could lead to the weakening of the Iranian regime and ultimately to the prevention of a war.
While many Iranians are said to support that country's nuclear program, there have been voices who in recent years questioning whether it is worth the sanctions, isolation, and threats of war the country is facing.
In 2006, Iran's largest reformist student group, Daftar Tahkim Vahdat, called for a temporary suspension of the country's sensitive nuclear work.
Earlier this year, a prominent Iranian religious scholar called for a debate among the country's intellectuals and activists about the safety of Iran's nuclear facilities.
-- Golnaz Esfandiari