April 24 (Reuters) - Fiserv FI.N missed Wall Street estimates for first-quarter revenue on Thursday, hurt by slowing demand in its payments processing unit, sending the company's shares down about 7% in premarket trading.

U.S. consumers have begun pulling back on discretionary spending amid worries of a potential economic slowdown brought on by the Trump administration's trade policies, affecting transaction volumes.

Wisconsin-based Fiserv collects fees from merchants, banks and credit unions for processing payments and transactions.

Processing revenue in the company's merchant solutions unit fell 9% to $276 million in the first quarter, while total merchant solutions revenue increased 5.3% to $2.37 billion.

Fiserv reported an adjusted revenue of $4.79 billion, compared with the average analyst estimate of $4.84 billion, according to data compiled by LSEG.

On an adjusted basis, the company earned $2.14 per share, beating estimates of $2.08.

(Reporting by Prakhar Srivastava in Bengaluru; Editing by Shounak Dasgupta)

((prakhar.srivastava2@thomsonreuters.com))