Christie's administration has already asked the state Supreme Court to weigh in on an earlier ruling by Jacobson, who ruled then that the state had to allow gay marriage.
Jacobson also ruled Thursday that the start of nuptials did not have to be delayed, finding the state was not likely to win its appeal and that it would not hurt the state if same-sex marriage licenses are issued.
Gay couples who want to wed "would suffer many hardships of constitutional magnitude if the stay were to be issued, but the state has not demonstrated how it would suffer in any meaningful way if the order is enforced," she wrote.
Thirteen states, including most in the Northeast, already allow gay couples to marry. New Jersey offers gay couples civil unions but not marriage.
The matter has been fought out in New Jersey's courts and Legislature for a decade.
"The court's decision once again confirms that the hardships of not being able to marry are real and immediate. Every day does count," said Hayley Gorenberg of Lambda Legal, which had filed a brief in support of same-sex couples seeking the right to marry.
Jacobson's earlier ruling found that it's unconstitutional for New Jersey to block gay marriage now that the federal government is giving married gay couples legal benefits.
New Jersey's attorney general said a state law cannot be found unconstitutional because of a change in federal policy.
Gay rights groups are also pushing lawmakers to override Christie's veto last year of a law that would have allowed gay marriage.