AMENDMENT to the SECOND LIEN GUARANTEE AND COLLATERAL AGREEMENT

Exhibit 10.25

AMENDMENT to the SECOND LIEN GUARANTEE AND COLLATERAL AGREEMENT

This Amendment to the Second Lien Guarantee and Collateral Agreement, dated as of September 27, 2005, made by Rosetta Resources, Inc., a Delaware corporation, Rosetta Resources Offshore, LLC, a Delaware limited liability company, Rosetta Resources Operating LP, a Delaware limited partnership, Rosetta Resources Holdings, LLC, a Delaware limited liability company, Rosetta Resources Operating GP, LLC, a Delaware limited liability company, in favor of BNP Paribas, as administrative agent (in such capacity, the “Administrative Agent”) for the banks and other financial institutions (the “Lenders”) parties to the Credit Agreement referred to below. All capitalized terms not defined herein shall have the meaning ascribed to them in such Credit Agreement.

W I T N E S S E T H:

WHEREAS, Rosetta Resources Inc. (the “Borrower”), the Lenders, the Administrative Agent and the other Agents, have entered into a Second Lien Term Loan Agreement, dated as of July 7, 2005 (as amended, supplemented or otherwise modified from time to time, the “Credit Agreement”);

WHEREAS, in connection with the Credit Agreement, the Borrower and certain of its Subsidiaries have entered into the Guarantee and Collateral Agreement, dated as of July 7, 2005 (as amended, supplemented or otherwise modified from time to time, the “Second Lien Guarantee and Collateral Agreement”) in favor of the Administrative Agent for the benefit of the Lenders and Affiliates of the Lenders;

WHEREAS, Rosetta Resources Inc. has recently restructured its subsidiaries;

NOW, THEREFORE, IT IS AGREED:

1. Guarantee and Collateral Agreement. The Second Lien Guarantee and Collateral Agreement is hereby amended by amending and restating Schedules 1 through 4 with the Schedules 1 through 4 attached hereto.

2. Governing Law. THIS ASSUMPTION AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAW OF THE STATE OF TEXAS.

IN WITNESS WHEREOF, the undersigned has caused this Assumption Agreement to be duly executed and delivered as of the date first above written.

[Signatures begin on the next page]

Amendment to Guarantee and Collateral Agreement - 1

Amendment to Guarantee and Collateral Agreement - 2

SCHEDULE 1

NOTICE ADDRESS OF OBLIGORS

Schedule 1 - 1

SCHEDULE 2

DESCRIPTION OF PLEDGED SECURITIES

Schedule 2 - 1

SCHEDULE 3

FILINGS AND OTHER ACTIONS

REQUIRED TO PERFECT SECURITY INTERESTS

Uniform Commercial Code Filings

Delivery to Administrative Agent of Pledged Securities

Deposit Account

The execution of the Blocked Account Control Agreement by and among the Borrower, the Administrative Agent and the depository bank named therein, granting the Administrative Agent “control” over the Margin Account.

Schedule 3 - 1

SCHEDULE 4

Rosetta Resources Inc.

Other names and trade names used in the past five years: None

Rosetta Resources Offshore, LLC

Rosetta Resources Operating LP

Rosetta Resources Holdings, LLC

Rosetta Resources Operating GP, LLC

Schedule 4 - 1